Minimum Cost Path with Alternating Directions I — C++

// Time:  O(1)
// Space: O(1)

// math
class Solution {
public:
    int minCost(int m, int n) {
        if (m == 1 && n == 1) {
            return 1;
        }
        if ((m == 1 && n == 2) || (m == 2 && n == 1)) {
            return 3;
        }
        return -1;
    }
};