256. Paint House

Let costs[i][0] be the minimal cost for painting house i red, so we have costs[i][0] += min(costs[i-1][1], costs[i-1][2]). Same to blue and green.

1:  class Solution {  
2:  public:  
3:    int minCost(vector<vector<int>>& costs) {  
4:      int n = costs.size();  
5:      for (int i = 1; i < n; i++) {  
6:        costs[i][0] += min(costs[i-1][1], costs[i-1][2]);  
7:        costs[i][1] += min(costs[i-1][0], costs[i-1][2]);  
8:        costs[i][2] += min(costs[i-1][0], costs[i-1][1]);  
9:      }  
10:      return n == 0 ? 0 : min(costs[n-1][0], min(costs[n-1][1], costs[n-1][2]));  
11:    }  
12:  };