LeetCode - Refresh - Reverse Bits

Two method of making that:

1. As we know this is 32 bit integer. We just get the bit and shift to 31 - i.

 1 class Solution {
 2 public:
 3     uint32_t reverseBits(uint32_t n) {
 4         uint32_t result;
 5         for (int i = 0; i < 32; i++) {
 6             result |= ((n >> i) & 1) << (31 - i);
 7         }
 8         return result;
 9     }
10 };

2. Swap bits

 1 class Solution {
 2 public:
 3     uint32_t swapBits(uint32_t n, int i, int j) {
 4         int first = (n >> i) & 1, second = (n >> j) & 1;
 5         if (first ^ second) {
 6             n ^= (1U << i) | (1U << j);
 7         }
 8         return n;
 9     }
10     uint32_t reverseBits(uint32_t n) {
11         for (int i = 0; i < 16; i++) {
12             n = swapBits(n, i, 31-i);
13         }
14         return n;
15     }
16 };

posted on 2015-03-23 05:50 keepshuatishuati 阅读(108) 评论(0) 编辑收藏举报