*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.

public class Solution {
public int minCost(int[][] costs) {
    if(costs==null||costs.length==0){
        return 0;
    }
    for(int i=1; i<costs.length; i++){
        costs[i][0] += Math.min(costs[i-1][1],costs[i-1][2]);
        costs[i][1] += Math.min(costs[i-1][0],costs[i-1][2]);
        costs[i][2] += Math.min(costs[i-1][1],costs[i-1][0]);
    }
    int n = costs.length-1;
    return Math.min(Math.min(costs[n][0], costs[n][1]), costs[n][2]);
}
}

reference: https://leetcode.com/discuss/51721/simple-java-dp-solution