minimum-domino-rotations-for-equal-row.cpp

class Solution {
public:
    int minDominoRotations(vector<int>& A, vector<int>& B) {
        int count[7] = {0};
        for(int i =0;i < size(A);i++){
            if(A[i] == B[i]){
                count[A[i]]++;
            }
            else{
                count[A[i]]++;
                count[B[i]]++;
            }
        }
        // check enough?
        int minRoll = INT_MAX;
        for(int i = 1;i<=6;i++){
            // at most 2 numbers satisfy this condition
            if(count[i] == A.size()){
                // try roll A to i
                int aCount = 0;
                for(int j = 0;j < A.size();j++){
                    if(A[j] != i) aCount++;
                }
                // try roll B to i
                int bCount = 0;
                for(int j = 0;j < A.size();j++){
                    if(B[j] != i) bCount++;
                }
                minRoll = min(aCount, bCount);
            }
        }
        return minRoll == INT_MAX ? -1 : minRoll;
    }
};