Paint House

There are a row of n houses, each house can be painted with one of the 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 a n x 3 cost matrix. For example, costs[0][0] is the cost of painting house 0 with color red; costs[1][2] is the cost of painting house 1 with color green, and so on… Find the minimum cost to paint all houses.

Note:

All costs are positive integers.

Solution:

  1. public class Solution {
  2.   public int minCost(int[][] costs) {
  3.     if (costs == null || costs.length == 0) {
  4.       return 0;
  5.     }
  7.     int n = costs.length;
  9.     for (int i = 1; i < n; i++) {
  10.       costs[i][0] += Math.min(costs[i - 1][1], costs[i - 1][2]);
  11.       costs[i][1] += Math.min(costs[i - 1][0], costs[i - 1][2]);
  12.       costs[i][2] += Math.min(costs[i - 1][1], costs[i - 1][0]);
  13.     }
  15.     return Math.min(Math.min(costs[n - 1][0], costs[n - 1][1]), costs[n - 1][2]);
  16.   }
  17. }