# 190. Reverse Bits(Solution || Leetcode easy || Java)

Reverse bits of a given 32 bits unsigned integer.

Note:

• Note that in some languages, such as Java, there is no unsigned integer type. In this case, both input and output will be given as a signed integer type. They should not affect your implementation, as the integer’s internal binary representation is the same, whether it is signed or unsigned.
• In Java, the compiler represents the signed integers using 2’s complement notation. Therefore, in Example 2 above, the input represents the signed integer `-3` and the output represents the signed integer `-1073741825`.

Example 1:

`Input: n = 00000010100101000001111010011100Output:    964176192 (00111001011110000010100101000000)Explanation: The input binary string 00000010100101000001111010011100 represents the unsigned integer 43261596, so return 964176192 which its binary representation is 00111001011110000010100101000000.`

Example 2:

`Input: n = 11111111111111111111111111111101Output:   3221225471 (10111111111111111111111111111111)Explanation: The input binary string 11111111111111111111111111111101 represents the unsigned integer 4294967293, so return 3221225471 which its binary representation is 10111111111111111111111111111111.`

Constraints:

• The input must be a binary string of length `32`

# SOLUTION:

`public class Solution {    // you need treat n as an unsigned value    public int reverseBits(int n) {        //Create a integer to store answer       int ans = 0;       //run the loop 32 times as it is given in constraints that       //the int is 32 bit long        for(int i = 0; i < 32; i++){            //append the last bit of integer to reverse it           ans |= (n & 1);                      //this condition is necessary anotherwise the loop will           // add a extra zero            if(i != 31)            //left shift ans to store next bit            ans = ans << 1;            //as the last bit is stored in ans remove that bit            n = n >> 1;        }        return ans;    }}`

Runtime 1 ms

Beats

97.45%

Memory 42.6 MB

Beats

34.36%

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