Given a positive integer n and you can do operations as follow:
- If n is even, replace n with n/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
Solution:
var map = {};
map[1] = 0;
var integerReplacement = function(n) {
if(n in map) return map[n];
if(n % 2 === 0) map[n] = integerReplacement(n / 2) + 1;
else map[n] = Math.min(integerReplacement(n + 1), integerReplacement(n - 1)) + 1;
return map[n];
};
