@@ -0,0 +1,31 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+class Solution {
+public:
+
+static bool cmp ( int a, int b )
+{
+int bitsa = 0;
+int bitsb = 0;
+int ta = a, tb = b;
+while( a != 0 )
+{
+if ( a%2 == 1 )
+bitsa++;
+a /= 2;
+}
+while( b != 0 )
+{
+if ( b%2 == 1 )
+bitsb++;
+b /= 2;
+}
+return ( bitsa != bitsb ? bitsa < bitsb : ta < tb);
+}
+
+vector<int> sortByBits ( vector<int>& arr ) {
+sort( arr.begin(), arr.end(), cmp );
+return arr;
+}
+};