ash: 079-1 in C++

1 files changed, 43 insertions, 0 deletions

diff --git a/challenge-079/ash/cpp/ch-1.cpp b/challenge-079/ash/cpp/ch-1.cpp
new file mode 100644
index 0000000000..27596b8967
--- /dev/null
+++ b/challenge-079/ash/cpp/ch-1.cpp
@@ -0,0 +1,43 @@
+/*
+    Task 1 from
+    https://perlweeklychallenge.org/blog/perl-weekly-challenge-079/
+*/
+
+#include <iostream>
+#include <sstream>
+
+using namespace std;
+
+int main(int argc, char** argv) {
+    if (argc != 2) {
+        cerr << "Usage: ./a.out 42" << endl;
+        return 1;
+    }
+
+    stringstream input(argv[1]);
+  
+    int n;
+    input >> n;
+
+    int total_bits = 0;
+    int scale = 1;
+    n++;
+    while (scale <= n) {
+        int scale2 = scale << 1;
+        
+        int fill_full = n / scale2;
+        int fill_frac = n % scale2;
+
+        int bits_full = fill_full * scale;
+        int bits_frac = 0;
+        if (fill_frac > scale) {
+            bits_frac = fill_frac - scale;
+        }
+
+        total_bits += bits_full + bits_frac;
+
+        scale = scale2;
+    }
+
+    cout << "There are " << total_bits << " set bits in the sequence from 1 to " << n << endl;
+}