397. Integer Replacement
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
1. Analyse
Recursion Algorithm.
2. AC Code
class Solution { public: int integerReplacement(int n) { return (int)integerReplacement((long)n); }
long integerReplacement(long n){
if( n <= 3 ) return (n-1);
else return ( n%2 ? min(integerReplacement(n+1),integerReplacement(n-1))+1 : integerReplacement(n/2)+1 );
} };
