[贪心] leetcode 1007 Minimum Domino Rotations For Equal Row

problem:https://leetcode.com/problems/minimum-domino-rotations-for-equal-row/

       有四种可能性，相等数字为A[0]，出现在上面或下面；相等数字为B[0]，出现在上面或下面。取这四者最小值即可。

class Solution {
public:
    int n;
    int minR(vector<int>& A, vector<int>& B, int target)
    {
        int res = 0;
        for(int i = 0; i < n; i++)
        {
            if(A[i] == target) { }
            else if(B[i] == target) res++;
            else return INT_MAX;
            
        }
        return res;
    }
    int minDominoRotations(vector<int>& A, vector<int>& B) {
        n = A.size();
        
        int res = min(min(minR(A, B, A[0]),minR(B, A, B[0])),min(minR(B, A, A[0]),minR(A, B, B[0])));
        return res == INT_MAX ? -1 : res;
    }
};