leetcode256 -- Paint House I

# 小郑之家~

### 题目

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.





class Solution {
public:
int minCost(vector<vector<int>>& costs) {
if (costs.empty() || costs[0].empty()) return 0;
vector<vector<int>> dp = costs;
for (int i = 1; i < dp.size(); ++i) {
for (int j = 0; j < 3; ++j) {
dp[i][j] += min(dp[i - 1][(j + 1) % 3], dp[i - 1][(j + 2) % 3]);
}
}
return min(min(dp.back()[0], dp.back()[1]), dp.back()[2]);
}
};



class Solution {
public:
int minCost(vector<vector<int>>& costs) {
if (costs.empty() || costs[0].empty()) return 0;
vector<vector<int>> dp = costs;
for (int i = 1; i < dp.size(); ++i) {
dp[i][0] += min(dp[i - 1][1], dp[i - 1][2]);
dp[i][1] += min(dp[i - 1][0], dp[i - 1][2]);
dp[i][2] += min(dp[i - 1][0], dp[i - 1][1]);
}
return min(min(dp.back()[0], dp.back()[1]), dp.back()[2]);
}
};