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

Solutions to Chapter 19 | Moderate
19.4 Write a method which finds the maximum of two numbers. You should not use if-else
or any other comparison operator.
EXAMPLE
Input: 5, 10
Output: 10
SOLUTION
pg 89
Let’s try to solve this by “re-wording” the problem. We will re-word the problem until we get
something that has removed all if statements.
Rewording 1: If a > b, return a; else, return b.
Rewording 2: If (a - b) is negative, return b; else, return a.
Rewording 3: If (a - b) is negative, let k = 1; else, let k = 0. Return a - k * (a - b).
Rewording 4: Let c = a - b. Let k = the most significant bit of c. Return a - k * c.
We have now reworded the problem into something that fits the requirements. The code
for this is below.
1 int getMax(int a, int b) {
2 int c = a - b;
3 int k = (c >> 31) & 0x1;
4 int max = a - k * c;
5 return max;
6 }
2 6 9
Cracking the Coding Interview | Additional Review Problems