1. 不用加减乘除做加法 public int Add(int a, int b) { int res = a; while(b != 0){ res = a ^ b; b = (a & b) << 1; a = res; } return res; } 2. 位1的个数 public int HammingWeight(uint n) { int req = 0; while(n != 0){ n -= n & (~n + 1); req++; } return req; }