397. 整数替换

class Solution 
{
public:
    int integerReplacement(int n) 
    {
        return DFS(n);
    }

    long long DFS(long long n)
    {
        if(n == 1) return 0;
        if(n & 1) return min(DFS(n + 1),DFS(n - 1)) + 1;
        else return DFS(n/2) + 1;
    }
};