LeetCode 397. Integer Replacement

Posted 2020-08-17 Black_Knight

Given a positive integer n and you can do operations as follow:

 

1. If n is even, replace n with n/2.
2. If n is odd, you can replace n with either n + 1 or n - 1.

What is the minimum number of replacements needed for n to become 1?

Example 1:

Input:
8

Output:
3

Explanation:
8 -> 4 -> 2 -> 1

Example 2:

Input:
7

Output:
4

Explanation:
7 -> 8 -> 4 -> 2 -> 1
or
7 -> 6 -> 3 -> 2 -> 1

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1. 递归

1 public class Solution {
2     public int integerReplacement(int n) {
3         if(n == 1) return 0;
4         if(n%2 == 0) return integerReplacement(n/2) + 1;
5         return 1 + Math.min(integerReplacement(n+1), integerReplacement(n-1));
6     }
7 }