- Added guest solutions by Laurent Rosenfeld.

16 files changed, 437 insertions, 0 deletions

diff --git a/challenge-175/laurent-rosenfeld/awk/ch-2.awk b/challenge-175/laurent-rosenfeld/awk/ch-2.awk
new file mode 100644
index 0000000000..959d5adeba
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/awk/ch-2.awk
@@ -0,0 +1,31 @@
+function gcd (i, j) {
+    while(j != 0) {
+        k = j
+        j = i % j
+        i = k
+    }
+    return i
+}
+function is_perfect_totient (num) {
+    tot = 0
+    for (i = 1; i < num; i++) {
+        if (gcd(num, i) == 1) {
+            tot += 1
+        }
+    }
+    sum = tot + cache[tot]
+    cache[num] = sum
+    return num == sum
+}
+BEGIN {
+    j = 1
+    count = 0
+    while (count < 20) {
+        if (is_perfect_totient(j)) {
+            printf "%d ", j
+            count += 1
+        }
+        j += 1
+    }
+    print " "
+}
diff --git a/challenge-175/laurent-rosenfeld/bc/ch-2.bc b/challenge-175/laurent-rosenfeld/bc/ch-2.bc
new file mode 100644
index 0000000000..d7bb3b48ea
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/bc/ch-2.bc
@@ -0,0 +1,33 @@
+define gcd (i, j) {
+    while(j != 0) {
+        k = j
+        j = i % j
+        i = k
+    }
+    return i
+}
+
+define is_perfect_totient (num) {
+    tot = 0
+    for (i = 1; i < num; i++) {
+        if (gcd(num, i) == 1) {
+            tot += 1
+        }
+    }
+    sum = tot + cache[tot]
+    cache[num] = sum
+    return num == sum
+}
+
+j = 1
+count = 0
+# we only go to 15 (not 20) because bc is very slow
+while (count <= 15) {
+    if (is_perfect_totient(j)) {
+        print j, " "
+        count += 1
+    }
+    j += 1
+}
+print "\n"
+quit
diff --git a/challenge-175/laurent-rosenfeld/c/ch-2.c b/challenge-175/laurent-rosenfeld/c/ch-2.c
new file mode 100644
index 0000000000..3aabbdabda
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/c/ch-2.c
@@ -0,0 +1,38 @@
+#include <stdio.h>
+#define MAX_VAL 50000
+
+int cache[MAX_VAL];
+
+int gcd(int i, int j) {
+    while (j != 0) {
+        int temp = i % j;
+        i = j;
+        j = temp;
+    }
+    return i;
+}
+
+int is_perfect_totient (int num) {
+    int tot = 0;
+    for (int i = 1; i < num; i++) {
+        if (gcd(num, i) == 1) {
+            tot++;
+        }
+    }
+    int sum = tot + cache[tot];
+    cache[num] = sum;
+    return num == sum;
+}
+
+int main() {
+    int j = 1;
+    int count = 0;
+    while (count < 20) {
+        if (is_perfect_totient(j)) {
+            printf("%d ", j);
+            count++;
+        }
+        j++;
+    }
+    printf("%s\n", " ");
+}
diff --git a/challenge-175/laurent-rosenfeld/d/ch-2.d b/challenge-175/laurent-rosenfeld/d/ch-2.d
new file mode 100644
index 0000000000..5bd0fd30a1
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/d/ch-2.d
@@ -0,0 +1,29 @@
+import std.stdio;
+import std.numeric;
+
+int[10000] cache;
+
+bool is_perfect_totient(int num) {
+    int tot = 0;
+    for (int i = 1; i < num; i++) {
+        if (gcd(num, i) == 1) {
+            tot++;
+        }
+    }
+    int sum = tot + cache[tot];
+    cache[num] = sum;
+    return num == sum;
+}
+
+void main() {
+    int j = 1;
+    int count = 0;
+    while (count < 20) {
+        if (is_perfect_totient(j)) {
+            printf("%d ", j);
+            count++;
+        }
+        j++;
+    }
+    writeln(" ");
+}
diff --git a/challenge-175/laurent-rosenfeld/go/ch-2.go b/challenge-175/laurent-rosenfeld/go/ch-2.go
new file mode 100644
index 0000000000..5fd36c7d8a
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/go/ch-2.go
@@ -0,0 +1,37 @@
+import "fmt"
+
+var cache [10000]int
+
+func gcd(i int, j int) int {
+    for j != 0 {
+        temp := i % j
+        i = j
+        j = temp
+    }
+    return i
+}
+
+func is_perfect_totient(n int) bool {
+    tot := 0
+    for i := 1; i < n; i++ {
+        if gcd(n, i) == 1 {
+            tot++
+        }
+    }
+    sum := tot + cache[tot]
+    cache[n] = sum
+    return n == sum
+}
+
+func main() {
+    i := 0
+    count := 0
+    for count <= 20 {
+        if is_perfect_totient(i) {
+            fmt.Printf("%d ", i)
+            count++
+        }
+        i++
+    }
+    fmt.Println("")
+}
diff --git a/challenge-175/laurent-rosenfeld/java/PerfectTotient.java b/challenge-175/laurent-rosenfeld/java/PerfectTotient.java
new file mode 100644
index 0000000000..7f46773ec8
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/java/PerfectTotient.java
@@ -0,0 +1,37 @@
+public class PerfectTotient {
+
+    static int[] cache = new int[10000];
+
+    public static int gcd(int i, int j) {
+        while (j != 0) {
+            int temp = i % j;
+            i = j;
+            j = temp;
+        }
+        return i;
+    }
+    public static boolean isPerfectTotient(int n) {
+        int tot = 0;
+        for (int i = 1; i < n; i++) {
+            if (gcd(n, i) == 1) {
+                tot++;
+            }
+        }
+        int sum = tot + cache[tot];
+        cache[n] = sum;
+        return n == sum;
+    }
+
+    public static void main(String[] args) {
+        int i = 0;
+        int count = 0;
+        while (count < 20) {
+            if (isPerfectTotient(i)) {
+                System.out.printf("%d ", i);
+                count++;
+            }
+            i++;
+        }
+        System.out.printf("%s", "\n");
+    }
+}
diff --git a/challenge-175/laurent-rosenfeld/javascript/ch-2.js b/challenge-175/laurent-rosenfeld/javascript/ch-2.js
new file mode 100644
index 0000000000..7d837c23cb
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/javascript/ch-2.js
@@ -0,0 +1,35 @@
+var cache = new Array(10000)
+cache[0] = 0
+
+function gcd (i, j) {
+    while(j != 0) {
+        k = j
+        j = i % j
+        i = k
+    }
+    return i
+}
+
+function is_perfect_totient (n) {
+    let tot = 0
+    for (var i = 1; i < n; i++) {
+          if (gcd(n, i) == 1) {
+            tot++
+        }
+    }
+    sum = tot + cache[tot]
+    cache[n] = sum
+    return n == sum
+}
+
+let count = 0
+let i = 1
+while (count < 20) {
+    if (is_perfect_totient(i)) {
+        process.stdout.write(i + " ")
+
+        count++
+    }
+    i++
+}
+process.stdout.write("\n")
diff --git a/challenge-175/laurent-rosenfeld/julia/ch-1.jl b/challenge-175/laurent-rosenfeld/julia/ch-1.jl
new file mode 100644
index 0000000000..7c869b02cd
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/julia/ch-1.jl
@@ -0,0 +1,12 @@
+using Dates
+
+function sundays(year, month)
+    month_end = Dates.lastdayofmonth(Dates.Date(year, month, 1))
+    weekday = Dates.dayofweek(month_end)
+    println(month_end - Dates.Day(weekday % 7))
+end
+
+year = parse( Int, ARGS[1])
+for month in 1:12
+    sundays(year, month)
+end
diff --git a/challenge-175/laurent-rosenfeld/julia/ch-2.jl b/challenge-175/laurent-rosenfeld/julia/ch-2.jl
new file mode 100644
index 0000000000..91ffaa7aa9
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/julia/ch-2.jl
@@ -0,0 +1,19 @@
+function is_perfect_totient(num)
+    n = num
+    sum = 0
+    while n >= 1
+        n = length( filter((x) -> gcd(x, n) == 1, 1:n-1))
+        sum += n
+    end
+    return num == sum
+end
+
+count = 0
+n = 1
+while count < 20
+    if is_perfect_totient(n)
+        print("$n ")
+        global count += 1
+    end
+    global n += 1;
+end
diff --git a/challenge-175/laurent-rosenfeld/kotlin/ch-2.kt b/challenge-175/laurent-rosenfeld/kotlin/ch-2.kt
new file mode 100644
index 0000000000..7616fe9219
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/kotlin/ch-2.kt
@@ -0,0 +1,37 @@
+val cache = Array(10000, {i-> 0})
+
+fun gcd (m: Int, n: Int): Int {
+    var i = m
+    var j = n
+    while(j != 0) {
+        val k = j
+        j = i % j
+        i = k
+    }
+    return i
+}
+
+fun is_perfect_totient(n: Int): Boolean {
+    var tot = 0
+    for (i in 1..n-1) {
+        if (gcd(n, i) == 1) {
+            tot++
+        }
+    }
+    val sum = tot + cache[tot]
+    cache[n] = sum
+    return n == sum
+}
+
+fun main() {
+    var i = 0
+    var count = 0
+    while (count <= 20) {
+        if (is_perfect_totient(i)) {
+            print("$i ")
+            count++
+        }
+        i++
+    }
+    println(" ")
+}
diff --git a/challenge-175/laurent-rosenfeld/nim/ch-2.nim b/challenge-175/laurent-rosenfeld/nim/ch-2.nim
new file mode 100644
index 0000000000..3bc982cf89
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/nim/ch-2.nim
@@ -0,0 +1,21 @@
+import math
+
+var cache: array[0..10000, int]
+
+proc is_perfect_totient (n: int): bool =
+  var tot = 0
+  for i in 1..n-1:
+    if (gcd(n, i) == 1):
+      tot += 1
+  let sum = tot + cache[tot]
+  cache[n] = sum
+  return sum == n
+
+var i = 1
+var count = 0
+while count < 20:
+  if is_perfect_totient(i):
+    stdout.write i, " "
+    count += 1
+  i += 1
+echo ""
diff --git a/challenge-175/laurent-rosenfeld/python/ch-1.py b/challenge-175/laurent-rosenfeld/python/ch-1.py
new file mode 100644
index 0000000000..78e40c3d33
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/python/ch-1.py
@@ -0,0 +1,23 @@
+from datetime import date,timedelta
+import sys
+
+def lastsundays (y):
+  for m in range(1,13):
+    if m == 12:
+      year = y + 1
+      month = 1
+    else:
+      year = y
+      month = m + 1
+
+    mthEnd = date(year, month, 1) - timedelta(days = 1)
+    weekDay = mthEnd.weekday()
+    lastSun = mthEnd - timedelta(days = (weekDay + 1) % 7)
+    print(lastSun)
+
+if len(sys.argv) == 2:
+  year = int(sys.argv[1])
+else:
+  year = 2022
+
+lastsundays(year)
diff --git a/challenge-175/laurent-rosenfeld/python/ch-2.py b/challenge-175/laurent-rosenfeld/python/ch-2.py
new file mode 100644
index 0000000000..d465124687
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/python/ch-2.py
@@ -0,0 +1,13 @@
+import math
+
+cache = [0] * 10000
+
+def is_perfect_totient (n):
+    tot = 0
+    for i in range(1, n):
+        if (math.gcd(n, i) == 1):
+            tot += 1
+
+​ sum = tot + cache[tot] ​ cache[n] = sum ​ return n == sum
+​
+i = 1 ​ count = 0 ​ while count < 20: ​ if isperfecttotient(i): ​ print(i, end = ” “) ​ count += 1 ​ i += 1 ​ print(” “)
diff --git a/challenge-175/laurent-rosenfeld/ring/ch-2.ring b/challenge-175/laurent-rosenfeld/ring/ch-2.ring
new file mode 100644
index 0000000000..a0c394adac
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/ring/ch-2.ring
@@ -0,0 +1,33 @@
+t_start = clock()
+j = 1
+count = 0
+cache = list(10000)
+while count < 14
+    if is_perfect_totient(j)
+        see "" + j + " "
+        count++
+    ok
+    j++
+end
+see nl
+duration = (clock() - t_start)/clockspersecond()
+see "" + duration + nl
+
+func gcd (i, j)
+    while j != 0
+        k = i % j
+        i = j
+        j = k
+    end
+    return i
+
+func is_perfect_totient (num)
+    tot = 0
+    for i = 1 to (num-1)
+        if gcd(num, i) = 1
+            tot++
+        ok
+    next
+    sum = tot + cache[tot+1]
+    cache[num+1] = sum
+    return num = sum
diff --git a/challenge-175/laurent-rosenfeld/ruby/ch-1.rb b/challenge-175/laurent-rosenfeld/ruby/ch-1.rb
new file mode 100644
index 0000000000..e92135e413
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/ruby/ch-1.rb
@@ -0,0 +1,9 @@
+require 'date'
+
+year = ARGV.shift.to_i.nil? || 2022
+
+for month in 1..12
+    lmd = Date.new(year, month, 1).next_month.prev_day
+    weekday = lmd.wday
+    puts lmd - (weekday % 7)
+end
diff --git a/challenge-175/laurent-rosenfeld/rust/ch-2.rs b/challenge-175/laurent-rosenfeld/rust/ch-2.rs
new file mode 100644
index 0000000000..dd4c284f75
--- /dev/null
+++ b/challenge-175/laurent-rosenfeld/rust/ch-2.rs
@@ -0,0 +1,30 @@
+use num::integer::gcd;
+
+static mut CACHE:[i32;10000] = [0; 10000];
+
+fn is_perfect_totient(n: i32) -> bool {
+    let mut  tot = 0;
+    for i in 1..n {
+        if gcd(n, i) == 1 {
+            tot += 1
+        }
+    }
+    unsafe {
+        let sum = tot + CACHE[tot as usize];
+        CACHE[n as usize] = sum;
+        return n == sum;
+    }
+}
+
+fn main() {
+    let mut i = 1;
+    let mut count = 0;
+    while count < 20 {
+        if is_perfect_totient(i) {
+            print!("{} ", i);
+            count += 1;
+        }
+        i += 1;
+    }
+    println!("{}", " ")
+}