Paint House II

https://leetcode.com/problems/paint-house-ii/

1）DP坐标型；

2）下一个col是根据前一个col来进行变化；

class Solution {
public:
    int minCostII(vector<vector<int>>& costs) {
        int n = costs.size();
        if(n == 0 || costs[0].size() == 0)
        {
            return 0;
        }

        int k = costs[0].size();

        int min1 = -1;
        int min2 = -1;

        for(int i = 0; i<n; i++)
        {
            int last1 = min1;
            int last2 = min2;
            min1 = -1;
            min2 = -1;

            for(int j = 0; j<k; j++)
            {
                if(j != last1)
                {
                    costs[i][j] += last1 < 0 ? 0 : costs[i-1][last1];
                }
                else
                {
                    costs[i][j] += last2 < 0 ? 0 : costs[i-1][last2];
                }

                if(min1 < 0 || costs[i][j] < costs[i][min1])
                {
                    min2 = min1;
                    min1 = j;
                }
                else if(min2 < 0 || costs[i][j] < costs[i][min2])
                {
                    min2 = j;
                }
            }
        }

        return costs[n-1][min1];
    }
};