190. Reverse Bits
Reverse bits of a given 32 bits unsigned integer.
Example 1:
Input: 00000010100101000001111010011100 Output: 00111001011110000010100101000000 Explanation: The input binary string 00000010100101000001111010011100 represents the unsigned integer 43261596, so return 964176192 which its binary representation is 00111001011110000010100101000000.
Example 2:
Input: 11111111111111111111111111111101 Output: 10111111111111111111111111111111 Explanation: The input binary string 11111111111111111111111111111101 represents the unsigned integer 4294967293, so return 3221225471 which its binary representation is 10101111110010110010011101101001.
Note:
-3 and the output represents the signed integer -1073741825.
Follow up:
If this function is called many times, how would you optimize it?
package leetcode.easy;
public class ReverseBits {
// you need treat n as an unsigned value
public int reverseBits(int n) {
int result = 0;
for (int i = 0; i < 32; i++) {
result += n & 1;
n >>>= 1; // CATCH: must do unsigned shift
if (i < 31) { // CATCH: for last digit, don‘t shift!
result <<= 1;
}
}
return result;
}
@org.junit.Test
public void test() {
System.out.println(reverseBits(-3));
}
}
原文：https://www.cnblogs.com/denggelin/p/11701594.html