Add C and C++ solutions

10 files changed, 475 insertions, 219 deletions

diff --git a/challenge-205/paulo-custodio/c/ch-1.c b/challenge-205/paulo-custodio/c/ch-1.c
new file mode 100644
index 0000000000..d5243c079c
--- /dev/null
+++ b/challenge-205/paulo-custodio/c/ch-1.c
@@ -0,0 +1,71 @@
+/*
+Challenge 205
+
+Task 1: Third Highest
+Submitted by: Mohammad S Anwar
+
+You are given an array of integers.
+
+Write a script to find out the Third Highest if found otherwise return the maximum.
+Example 1
+
+Input: @array = (5,3,4)
+Output: 3
+
+First highest is 5. Second highest is 4. Third highest is 3.
+
+Example 2
+
+Input: @array = (5,6)
+Output: 6
+
+First highest is 6. Second highest is 5. Third highest is missing, so maximum is returned.
+
+Example 3
+
+Input: @array = (5,4,4,3)
+Output: 3
+
+First highest is 5. Second highest is 4. Third highest is 3.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+
+int compare_desc(const void* a, const void* b) {
+    return *(int*)b - *(int*)a;
+}
+
+int main(int argc, char* argv[]) {
+    argv++; argc--;
+    int result = 0;
+
+    if (argc > 0) {
+        int num_items = argc;
+        int* items = malloc(num_items * sizeof(int));
+
+        // parse input numbers
+        for (int i = 0; i < num_items; i++)
+            items[i] = atoi(argv[i]);
+
+        // sort descending
+        qsort(items, num_items, sizeof(int), compare_desc);
+
+        // remove duplicates
+        int last = items[0]+1;  // different from first
+        int j = 0;
+        for (int i = 0; i < num_items; i++) {
+            if (items[i] != last)
+                items[j++] = last = items[i];
+        }
+        num_items = j;
+
+        // output
+        result = (num_items < 3) ? items[0] : items[2];
+
+        free(items);
+    }
+
+    printf("%d\n", result);
+    return EXIT_SUCCESS;
+}
diff --git a/challenge-205/paulo-custodio/c/ch-2.c b/challenge-205/paulo-custodio/c/ch-2.c
new file mode 100644
index 0000000000..78c8f07ab1
--- /dev/null
+++ b/challenge-205/paulo-custodio/c/ch-2.c
@@ -0,0 +1,61 @@
+/*
+Challenge 205
+
+Task 2: Maximum XOR
+Submitted by: Mohammad S Anwar
+
+You are given an array of integers.
+
+Write a script to find the highest value obtained by XORing any two distinct members of the array.
+Example 1
+
+Input: @array = (1,2,3,4,5,6,7)
+Output: 7
+
+The maximum result of 1 xor 6 = 7.
+
+Example 2
+
+Input: @array = (2,4,1,3)
+Output: 7
+
+The maximum result of 4 xor 3 = 7.
+
+Example 3
+
+Input: @array = (10,5,7,12,8)
+Output: 15
+
+The maximum result of 10 xor 5 = 15.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char* argv[]) {
+    argv++; argc--;
+    int result = -1;
+
+    if (argc > 0) {
+        int num_items = argc;
+        int* items = malloc(num_items * sizeof(int));
+
+        // parse input numbers
+        for (int i = 0; i < num_items; i++)
+            items[i] = atoi(argv[i]);
+
+        // compute max of xor of all pairs
+        for (int i = 0; i < num_items-1; i++) {
+            for (int j = i+1; j < num_items; j++) {
+                int n = items[i] ^ items[j];
+                if (n > result)
+                    result = n;
+            }
+        }
+
+        free(items);
+    }
+
+    printf("%d\n", result);
+    return EXIT_SUCCESS;
+}
diff --git a/challenge-205/paulo-custodio/cpp/ch-1.cpp b/challenge-205/paulo-custodio/cpp/ch-1.cpp
new file mode 100644
index 0000000000..54e83bebfb
--- /dev/null
+++ b/challenge-205/paulo-custodio/cpp/ch-1.cpp
@@ -0,0 +1,65 @@
+/*
+Challenge 205
+
+Task 1: Third Highest
+Submitted by: Mohammad S Anwar
+
+You are given an array of integers.
+
+Write a script to find out the Third Highest if found otherwise return the maximum.
+Example 1
+
+Input: @array = (5,3,4)
+Output: 3
+
+First highest is 5. Second highest is 4. Third highest is 3.
+
+Example 2
+
+Input: @array = (5,6)
+Output: 6
+
+First highest is 6. Second highest is 5. Third highest is missing, so maximum is returned.
+
+Example 3
+
+Input: @array = (5,4,4,3)
+Output: 3
+
+First highest is 5. Second highest is 4. Third highest is 3.
+*/
+
+#include <algorithm>
+#include <iostream>
+#include <vector>
+
+int main(int argc, char* argv[]) {
+    argv++; argc--;
+    int result = 0;
+
+    if (argc > 0) {
+        std::vector<int> items;
+
+        // parse input numbers
+        for (int i = 0; i < argc; i++)
+            items.push_back(atoi(argv[i]));
+
+        // sort descending
+        std::sort(items.rbegin(), items.rend());
+
+        // remove duplicates
+        int last = items[0]+1;  // different from first
+        size_t j = 0;
+        for (size_t i = 0; i < items.size(); i++) {
+            if (items[i] != last)
+                items[j++] = last = items[i];
+        }
+        items.resize(j);
+
+        // output
+        result = (items.size() < 3) ? items[0] : items[2];
+    }
+
+    std::cout << result << std::endl;
+    return EXIT_SUCCESS;
+}
diff --git a/challenge-205/paulo-custodio/cpp/ch-2.cpp b/challenge-205/paulo-custodio/cpp/ch-2.cpp
new file mode 100644
index 0000000000..6eb130b24a
--- /dev/null
+++ b/challenge-205/paulo-custodio/cpp/ch-2.cpp
@@ -0,0 +1,59 @@
+/*
+Challenge 205
+
+Task 2: Maximum XOR
+Submitted by: Mohammad S Anwar
+
+You are given an array of integers.
+
+Write a script to find the highest value obtained by XORing any two distinct members of the array.
+Example 1
+
+Input: @array = (1,2,3,4,5,6,7)
+Output: 7
+
+The maximum result of 1 xor 6 = 7.
+
+Example 2
+
+Input: @array = (2,4,1,3)
+Output: 7
+
+The maximum result of 4 xor 3 = 7.
+
+Example 3
+
+Input: @array = (10,5,7,12,8)
+Output: 15
+
+The maximum result of 10 xor 5 = 15.
+*/
+
+#include <algorithm>
+#include <iostream>
+#include <vector>
+
+int main(int argc, char* argv[]) {
+    argv++; argc--;
+    int result = -1;
+
+    if (argc > 0) {
+        std::vector<int> items;
+
+        // parse input numbers
+        for (int i = 0; i < argc; i++)
+            items.push_back(atoi(argv[i]));
+
+        // compute max of xor of all pairs
+        for (size_t i = 0; i < items.size()-1; i++) {
+            for (size_t j = i+1; j < items.size(); j++) {
+                int n = items[i] ^ items[j];
+                if (n > result)
+                    result = n;
+            }
+        }
+    }
+
+    std::cout << result << std::endl;
+    return EXIT_SUCCESS;
+}
diff --git a/challenge-206/paulo-custodio/c/ch-1.c b/challenge-206/paulo-custodio/c/ch-1.c
index 61d77fb946..abb788e056 100644
--- a/challenge-206/paulo-custodio/c/ch-1.c
+++ b/challenge-206/paulo-custodio/c/ch-1.c
@@ -29,42 +29,42 @@ Output: 15
 #include <stdlib.h>
 
 int minutes(const char* str) {
-	int hours = 0, minutes = 0;
-	if (sscanf(str, "%d:%d", &hours, &minutes) == 2)
-		return hours*60+minutes;
-	else
-		return 0;
+    int hours = 0, minutes = 0;
+    if (sscanf(str, "%d:%d", &hours, &minutes) == 2)
+        return hours*60+minutes;
+    else
+        return 0;
 }
 
 int compare(const void* a, const void* b) {
-	return *(int*)a - *(int*)b;
+    return *(int*)a - *(int*)b;
 }
 
 int main(int argc, char* argv[]) {
-	argv++; argc--;
-	if (argc < 2) {
-		fputs("Usage: ch-1 time...\n", stderr);
-		return EXIT_FAILURE;
-	}
-	
-	int num_items = argc+1;
-	int* items = malloc(num_items * sizeof(int));
-	for (int i = 0; i < num_items-1; i++) 
-		items[i] = minutes(argv[i]);
-	qsort(items, num_items-1, sizeof(int), compare);
-	items[num_items-1] = items[0] + 24*60;
-	
-	int min = items[num_items-1] - items[0];
-	for (int i = 0; i < num_items-1; i++) {
-		for (int j = i+1; j < num_items; j++) {
-			int n = items[j] - items[i];
-			if (n < min)
-				min = n;
-		}
-	}
-	
-	printf("%d\n", min);
-	free(items);
-
-	return EXIT_SUCCESS;
+    argv++; argc--;
+    if (argc < 2) {
+        fputs("Usage: ch-1 time...\n", stderr);
+        return EXIT_FAILURE;
+    }
+
+    int num_items = argc+1;
+    int* items = malloc(num_items * sizeof(int));
+    for (int i = 0; i < num_items-1; i++)
+        items[i] = minutes(argv[i]);
+    qsort(items, num_items-1, sizeof(int), compare);
+    items[num_items-1] = items[0] + 24*60;
+
+    int min = items[num_items-1] - items[0];
+    for (int i = 0; i < num_items-1; i++) {
+        for (int j = i+1; j < num_items; j++) {
+            int n = items[j] - items[i];
+            if (n < min)
+                min = n;
+        }
+    }
+
+    printf("%d\n", min);
+    free(items);
+
+    return EXIT_SUCCESS;
 }
diff --git a/challenge-206/paulo-custodio/c/ch-2.c b/challenge-206/paulo-custodio/c/ch-2.c
index baed295d4c..79e72feeb5 100644
--- a/challenge-206/paulo-custodio/c/ch-2.c
+++ b/challenge-206/paulo-custodio/c/ch-2.c
@@ -41,94 +41,94 @@ So the maximum sum is 2.
 #define MAX(a,b) ((a) > (b) ? (a) : (b))
 
 typedef struct {
-	size_t count;
-	int* items;
+    size_t count;
+    int* items;
 } IList;
 
 IList* ilist_new(size_t count) {
-	IList* list = calloc(1, sizeof(IList));
-	assert(list);
-	if (count) {
-		list->count = count;
-		list->items = calloc(count, sizeof(int));
-		assert(list->items);
-	}
-	return list;
+    IList* list = calloc(1, sizeof(IList));
+    assert(list);
+    if (count) {
+        list->count = count;
+        list->items = calloc(count, sizeof(int));
+        assert(list->items);
+    }
+    return list;
 }
 
 void ilist_free(IList* list) {
-	free(list->items);
-	free(list);
+    free(list->items);
+    free(list);
 }
 
 void ilist_push(IList* list, int elem) {
-	list->count++;
-	list->items = realloc(list->items, list->count * sizeof(int));
-	assert(list->items);
-	list->items[list->count - 1] = elem;
+    list->count++;
+    list->items = realloc(list->items, list->count * sizeof(int));
+    assert(list->items);
+    list->items[list->count - 1] = elem;
 }
 
 void ilist_remove(IList* list, size_t index) {
-	assert(index < list->count);
-	memmove(&list->items[index], &list->items[index+1], (list->count - (index+1))*sizeof(int));
-	list->count--;
+    assert(index < list->count);
+    memmove(&list->items[index], &list->items[index+1], (list->count - (index+1))*sizeof(int));
+    list->count--;
 }
 
 IList* ilist_clone(IList* list) {
-	IList* copy = ilist_new(list->count);
-	assert(copy);
-	memcpy(copy->items, list->items, list->count * sizeof(int));
-	return copy;
+    IList* copy = ilist_new(list->count);
+    assert(copy);
+    memcpy(copy->items, list->items, list->count * sizeof(int));
+    return copy;
 }
 
 void compute_pairs_max(int* max, IList* set, IList* pending) {
-	if (pending->count == 0) {		// compute sum, set max
-		int sum = 0;
-		for (int i = 0; i < set->count; i += 2) {
-			int n = MIN(set->items[i], set->items[i + 1]);
-			sum += n;
-		}
-		*max = MAX(*max, sum);
-	}
-	else {							// recurse for each pair
-		for (int i = 0; i < pending->count - 1; i++) {
-			for (int j = i+1; j < pending->count; j++) {
-				IList* new_set = ilist_clone(set);
-				IList* new_pending = ilist_clone(pending);
-
-				ilist_push(new_set, pending->items[i]);
-				ilist_push(new_set, pending->items[j]);
-
-				ilist_remove(new_pending, j);
-				ilist_remove(new_pending, i);
-
-				compute_pairs_max(max, new_set, new_pending);
-
-				ilist_free(new_set);
-				ilist_free(new_pending);
-			}
-		}
-	}
+    if (pending->count == 0) {      // compute sum, set max
+        int sum = 0;
+        for (int i = 0; i < set->count; i += 2) {
+            int n = MIN(set->items[i], set->items[i + 1]);
+            sum += n;
+        }
+        *max = MAX(*max, sum);
+    }
+    else {                          // recurse for each pair
+        for (int i = 0; i < pending->count - 1; i++) {
+            for (int j = i+1; j < pending->count; j++) {
+                IList* new_set = ilist_clone(set);
+                IList* new_pending = ilist_clone(pending);
+
+                ilist_push(new_set, pending->items[i]);
+                ilist_push(new_set, pending->items[j]);
+
+                ilist_remove(new_pending, j);
+                ilist_remove(new_pending, i);
+
+                compute_pairs_max(max, new_set, new_pending);
+
+                ilist_free(new_set);
+                ilist_free(new_pending);
+            }
+        }
+    }
 }
 
 int main(int argc, char* argv[]) {
-	argv++; argc--;
-	if (argc % 2 != 0) {
-		fputs("usage: ch-2 pairs...\n", stderr);
-		return EXIT_FAILURE;
-	}
+    argv++; argc--;
+    if (argc % 2 != 0) {
+        fputs("usage: ch-2 pairs...\n", stderr);
+        return EXIT_FAILURE;
+    }
 
-	IList* set = ilist_new(0);
-	IList* pending = ilist_new(argc);
-	for (int i = 0; i < argc; i++)
-		pending->items[i] = atoi(argv[i]);
+    IList* set = ilist_new(0);
+    IList* pending = ilist_new(argc);
+    for (int i = 0; i < argc; i++)
+        pending->items[i] = atoi(argv[i]);
 
-	int max = 0;
-	compute_pairs_max(&max, set, pending);
-	printf("%d\n", max);
+    int max = 0;
+    compute_pairs_max(&max, set, pending);
+    printf("%d\n", max);
 
-	ilist_free(set);
-	ilist_free(pending);
+    ilist_free(set);
+    ilist_free(pending);
 
-	return EXIT_SUCCESS;
+    return EXIT_SUCCESS;
 }
diff --git a/challenge-206/paulo-custodio/cpp/ch-1.cpp b/challenge-206/paulo-custodio/cpp/ch-1.cpp
index 4845728f67..c866da59c5 100644
--- a/challenge-206/paulo-custodio/cpp/ch-1.cpp
+++ b/challenge-206/paulo-custodio/cpp/ch-1.cpp
@@ -32,38 +32,38 @@ Output: 15
 #include <vector>
 
 int minutes(const std::string& str) {
-	int hours = 0, minutes = 0;
-	char sep;
-	std::istringstream iss{ str };
-	if ((iss >> hours >> sep >> minutes) && sep == ':')
-		return hours * 60 + minutes;
-	else
-		return 0;
+    int hours = 0, minutes = 0;
+    char sep;
+    std::istringstream iss{ str };
+    if ((iss >> hours >> sep >> minutes) && sep == ':')
+        return hours * 60 + minutes;
+    else
+        return 0;
 }
 
 int main(int argc, char* argv[]) {
-	argv++; argc--;
-	if (argc < 2) {
-		std::cerr << "Usage: ch-1 time..." << std::endl;
-		return EXIT_FAILURE;
-	}
-
-	std::vector<int> items;
-	for (int i = 0; i < argc; i++)
-		items.push_back(minutes(argv[i]));
-	std::sort(items.begin(), items.end());
-	items.push_back(items.front() + 24 * 60);
-
-	int min = items.back() - items.front();
-	for (size_t i = 0; i < items.size() - 1; i++) {
-		for (size_t j = i + 1; j < items.size(); j++) {
-			int n = items[j] - items[i];
-			if (n < min)
-				min = n;
-		}
-	}
-
-	std::cout << min << std::endl;
-
-	return EXIT_SUCCESS;
+    argv++; argc--;
+    if (argc < 2) {
+        std::cerr << "Usage: ch-1 time..." << std::endl;
+        return EXIT_FAILURE;
+    }
+
+    std::vector<int> items;
+    for (int i = 0; i < argc; i++)
+        items.push_back(minutes(argv[i]));
+    std::sort(items.begin(), items.end());
+    items.push_back(items.front() + 24 * 60);
+
+    int min = items.back() - items.front();
+    for (size_t i = 0; i < items.size() - 1; i++) {
+        for (size_t j = i + 1; j < items.size(); j++) {
+            int n = items[j] - items[i];
+            if (n < min)
+                min = n;
+        }
+    }
+
+    std::cout << min << std::endl;
+
+    return EXIT_SUCCESS;
 }
diff --git a/challenge-206/paulo-custodio/cpp/ch-2.cpp b/challenge-206/paulo-custodio/cpp/ch-2.cpp
index 07f944b3b5..d91460649d 100644
--- a/challenge-206/paulo-custodio/cpp/ch-2.cpp
+++ b/challenge-206/paulo-custodio/cpp/ch-2.cpp
@@ -36,50 +36,50 @@ So the maximum sum is 2.
 #include <iostream>
 #include <vector>
 
-void compute_pairs_max(int& max, 
-	const std::vector<int>& set, const std::vector<int>& pending
+void compute_pairs_max(int& max,
+    const std::vector<int>& set, const std::vector<int>& pending
 ) {
-	if (pending.size() == 0) {		// compute sum, set max
-		int sum = 0;
-		for (size_t i = 0; i < set.size(); i += 2) {
-			int n = std::min(set[i], set[i + 1]);
-			sum += n;
-		}
-		max = std::max(max, sum);
-	}
-	else {							// recurse for each pair
-		for (size_t i = 0; i < pending.size() - 1; i++) {
-			for (size_t j = i+1; j < pending.size(); j++) {
-				std::vector<int> new_set = set;
-				std::vector<int> new_pending = pending;
-
-				new_set.push_back(pending[i]);
-				new_set.push_back(pending[j]);
-
-				new_pending.erase(new_pending.begin() + j);
-				new_pending.erase(new_pending.begin() + i);
-
-				compute_pairs_max(max, new_set, new_pending);
-			}
-		}
-	}
+    if (pending.size() == 0) {      // compute sum, set max
+        int sum = 0;
+        for (size_t i = 0; i < set.size(); i += 2) {
+            int n = std::min(set[i], set[i + 1]);
+            sum += n;
+        }
+        max = std::max(max, sum);
+    }
+    else {                          // recurse for each pair
+        for (size_t i = 0; i < pending.size() - 1; i++) {
+            for (size_t j = i+1; j < pending.size(); j++) {
+                std::vector<int> new_set = set;
+                std::vector<int> new_pending = pending;
+
+                new_set.push_back(pending[i]);
+                new_set.push_back(pending[j]);
+
+                new_pending.erase(new_pending.begin() + j);
+                new_pending.erase(new_pending.begin() + i);
+
+                compute_pairs_max(max, new_set, new_pending);
+            }
+        }
+    }
 }
 
 int main(int argc, char* argv[]) {
-	argv++; argc--;
-	if (argc % 2 != 0) {
-		std::cerr << "usage: ch-2 pairs..." << std::endl;
-		return EXIT_FAILURE;
-	}
-
-	std::vector<int> set;
-	std::vector<int> pending;
-	for (int i = 0; i < argc; i++)
-		pending.push_back(atoi(argv[i]));
-
-	int max = 0;
-	compute_pairs_max(max, set, pending);
-	std::cout << max << std::endl;
-
-	return EXIT_SUCCESS;
+    argv++; argc--;
+    if (argc % 2 != 0) {
+        std::cerr << "usage: ch-2 pairs..." << std::endl;
+        return EXIT_FAILURE;
+    }
+
+    std::vector<int> set;
+    std::vector<int> pending;
+    for (int i = 0; i < argc; i++)
+        pending.push_back(atoi(argv[i]));
+
+    int max = 0;
+    compute_pairs_max(max, set, pending);
+    std::cout << max << std::endl;
+
+    return EXIT_SUCCESS;
 }
diff --git a/challenge-206/paulo-custodio/perl/ch-1.pl b/challenge-206/paulo-custodio/perl/ch-1.pl
index 8e8d8602e3..6d0bb7cf05 100644
--- a/challenge-206/paulo-custodio/perl/ch-1.pl
+++ b/challenge-206/paulo-custodio/perl/ch-1.pl
@@ -4,24 +4,24 @@
 #
 # Task 1: Shortest Time
 # Submitted by: Mohammad S Anwar
-# 
+#
 # You are given a list of time points, at least 2, in the 24-hour clock format HH:MM.
-# 
+#
 # Write a script to find out the shortest time in minutes between any two time points.
 # Example 1
-# 
+#
 # Input: @time = ("00:00", "23:55", "20:00")
 # Output: 5
-# 
+#
 # Since the difference between "00:00" and "23:55" is the shortest (5 minutes).
-# 
+#
 # Example 2
-# 
+#
 # Input: @array = ("01:01", "00:50", "00:57")
 # Output: 4
-# 
+#
 # Example 3
-# 
+#
 # Input: @array = ("10:10", "09:30", "09:00", "09:55")
 # Output: 15
 
@@ -32,15 +32,15 @@ my @in = sort { $a <=> $b } map { minutes($_) } @ARGV;
 push @in, $in[0] + minutes("24:00");
 my $min = $in[-1] - $in[0];
 for my $i (0..$#in-1) {
-	for my $j ($i+1..$#in) {
-		my $n = $in[$j] - $in[$i];
-		$min = $n if $n < $min;
-	}
+    for my $j ($i+1..$#in) {
+        my $n = $in[$j] - $in[$i];
+        $min = $n if $n < $min;
+    }
 }
 say $min;
 
-sub minutes { 
-	my($t) = @_;
-	$t =~ /^(\d+):(\d+)$/ or die "invalid time $t\n";
-	return $1*60+$2;
+sub minutes {
+    my($t) = @_;
+    $t =~ /^(\d+):(\d+)$/ or die "invalid time $t\n";
+    return $1*60+$2;
 }
diff --git a/challenge-206/paulo-custodio/perl/ch-2.pl b/challenge-206/paulo-custodio/perl/ch-2.pl
index 17a17b0940..35f02b1fa9 100644
--- a/challenge-206/paulo-custodio/perl/ch-2.pl
+++ b/challenge-206/paulo-custodio/perl/ch-2.pl
@@ -4,32 +4,32 @@
 #
 # Task 2: Array Pairings
 # Submitted by: Mohammad S Anwar
-# 
+#
 # You are given an array of integers having even number of elements..
-# 
+#
 # Write a script to find the maximum sum of the minimum of each pairs.
 # Example 1
-# 
+#
 # Input: @array = (1,2,3,4)
 # Output: 4
-# 
+#
 # Possible Pairings are as below:
 # a) (1,2) and (3,4). So min(1,2) + min(3,4) => 1 + 3 => 4
 # b) (1,3) and (2,4). So min(1,3) + min(2,4) => 1 + 2 => 3
 # c) (1,4) and (2,3). So min(1,4) + min(2,3) => 2 + 1 => 3
-# 
+#
 # So the maxium sum is 4.
-# 
+#
 # Example 2
-# 
+#
 # Input: @array = (0,2,1,3)
 # Output: 2
-# 
+#
 # Possible Pairings are as below:
 # a) (0,2) and (1,3). So min(0,2) + min(1,3) => 0 + 1 => 1
 # b) (0,1) and (2,3). So min(0,1) + min(2,3) => 0 + 2 => 2
 # c) (0,3) and (2,1). So min(0,3) + min(2,1) => 0 + 1 => 1
-# 
+#
 # So the maximum sum is 2.
 
 use Modern::Perl;
@@ -40,35 +40,35 @@ my @in = @ARGV;
 my @pairs = all_pairs(@in);
 my $max = 0;
 for my $pair (@pairs) {
-	my $sum = sum(map { min(@$_) } @$pair);
-	$max = max($max, $sum);
+    my $sum = sum(map { min(@$_) } @$pair);
+    $max = max($max, $sum);
 }
 say $max;
 
 sub all_pairs {
-	my(@in) = @_;
-	my @pairs;
-	compute_pairs(\@pairs, [], [@in]);
-	return @pairs;
+    my(@in) = @_;
+    my @pairs;
+    compute_pairs(\@pairs, [], [@in]);
+    return @pairs;
 }
 
 sub compute_pairs {
-	my($pairs, $set, $pending) = @_;
-	my @set = @$set;
-	my @pending = @$pending;
-	if (@pending) {
-		for my $i (0..$#pending-1) {
-			for my $j ($i+1..$#pending) {
-				my @this_set = (@set, [$pending[$i], $pending[$j]]);
-				my @this_pending = @pending;
-				splice(@this_pending, $j, 1);
-				splice(@this_pending, $i, 1);
-				compute_pairs($pairs, \@this_set, \@this_pending);
-			}
-		}
-	}
-	else {
-		push @$pairs, [@$set];
-	}
+    my($pairs, $set, $pending) = @_;
+    my @set = @$set;
+    my @pending = @$pending;
+    if (@pending) {
+        for my $i (0..$#pending-1) {
+            for my $j ($i+1..$#pending) {
+                my @this_set = (@set, [$pending[$i], $pending[$j]]);
+                my @this_pending = @pending;
+                splice(@this_pending, $j, 1);
+                splice(@this_pending, $i, 1);
+                compute_pairs($pairs, \@this_set, \@this_pending);
+            }
+        }
+    }
+    else {
+        push @$pairs, [@$set];
+    }
 }
-	
+