Cracking the Coding Interview, 4 Edition - 150 Programming Interview Questions and Solutions

Solutions to Chapter 5 | Bit Manipulation
5.1 You are given two 32-bit numbers, N and M, and two bit positions, i and j. Write a
method to set all bits between i and j in N equal to M (e.g., M becomes a substring of
N located at i and starting at j).
EXAMPLE:
SOLUTION
Input: N = 10000000000, M = 10101, i = 2, j = 6
Output: N = 10001010100
pg 58
This code operates by clearing all bits in N between position i and j, and then ORing to put
M in there.
1 public static int updateBits(int n, int m, int i, int j) {
2 int max = ~0; /* All 1’s */
3
4 // 1’s through position j, then 0’s
5 int left = max - ((1