翻轉32位無符號二進制整數this
Reverse bits of a given 32 bits unsigned integer.spa
For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as 00111001011110000010100101000000).code
Follow up:
If this function is called many times, how would you optimize it?blog
1 public class Solution { 2 // you need treat n as an unsigned value 3 public int reverseBits(int n) { 4 int res = 0; 5 for(int i=0; i<32; i++) { 6 res = res + (n & 1); 7 if(i < 31) { 8 res = res << 1; 9 } 10 n = n >> 1; 11 } 12 return res; 13 } 14 }
另外一種寫法:input
1 public int reverseBits(int n) { 2 int res = 0; 3 for(int i=0; i<32; i++) { 4 if((n & 1) == 1) { 5 res = (res << 1) + 1; 6 } else { 7 res = res << 1; 8 } 9 n = n >> 1; 10 } 11 return res; 12 }
思路都是從右到左判斷0/1,加到res。it