Leetcode 256 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: simple DP

 public class Solution {  
   public int minCost(int[][] costs) {  
     int n=costs.length;  
     int red=0, blue=0, green=0;  
     for (int i=0; i<n; i++) {  
       if (i==0) {  
         red=costs[i][0];  
         blue=costs[i][1];  
         green=costs[i][2];  
       }  
       else {  
         int nextRed=costs[i][0]+Math.min(blue,green);  
         int nextBlue=costs[i][1]+Math.min(red,green);  
         green=costs[i][2]+Math.min(red,blue);  
         red=nextRed;  
         blue=nextBlue;  
       }  
     }  
     return Math.min(red,Math.min(blue,green));  
   }  
 }