256. Paint House

There is a row of n houses, where each house can be painted one of three colors: red, blue, or green. The cost of painting each house with a certain color is different. You have to paint all the houses such that no two adjacent houses have the same color.

The cost of painting each house with a certain color is represented by an n x 3 cost matrix costs.

• For example, costs[0][0] is the cost of painting house 0 with the color red; costs[1][2] is the cost of painting house 1 with color green, and so on…

Return the minimum cost to paint all houses.

class Solution {
public:
    int minCost(vector<vector<int>>& costs) {
        int r = 0, g = 0, b = 0;
        for(auto& c : costs) {
            int R = c[0], G = c[1], B = c[2];
            int nr = min(g,b) + R, ng = min(r,b) + G, nb = min(r,g) + B;
            r = nr, g = ng, b = nb;
        }
        return min({r,g,b});
    }
};