Paint House II

Author: sachuverma

Leetcode Daily Challenge/August-2021/Paint House II.cpp

@@ -0,0 +1,59 @@
+/*
+Paint House II
+=============
+
+There are a row of n houses, each house can be painted with one of the k colors. 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 an n x k cost matrix costs.
+
+For example, costs[0][0] is the cost of painting house 0 with color 0; costs[1][2] is the cost of painting house 1 with color 2, and so on...
+Return the minimum cost to paint all houses.
+
+Example 1:
+Input: costs = [[1,5,3],[2,9,4]]
+Output: 5
+Explanation:
+Paint house 0 into color 0, paint house 1 into color 2. Minimum cost: 1 + 4 = 5; 
+Or paint house 0 into color 2, paint house 1 into color 0. Minimum cost: 3 + 2 = 5.
+
+Example 2:
+Input: costs = [[1,3],[2,4]]
+Output: 5
+ 
+Constraints:
+costs.length == n
+costs[i].length == k
+1 <= n <= 100
+2 <= k <= 20
+1 <= costs[i][j] <= 20
+ 
+Follow up: Could you solve it in O(nk) runtime?
+*/
+
+class Solution {
+public:
+    int memo[101][22];
+    
+    int dfs(vector<vector<int>>& costs, int i, int prev_color) {
+        if(i == costs.size()) return 0;
+        
+        if(memo[i][prev_color+1] != -1) return memo[i][prev_color+1];
+        int ans = INT_MAX;
+        
+        for(int j=0; j<costs[i].size(); ++j) {
+            if(prev_color != j) {
+                int next = dfs(costs, i+1, j);
+                if(next != INT_MAX) 
+                    ans = min(ans, costs[i][j] + next);
+            }
+        }
+        
+        return memo[i][prev_color+1] = ans;
+    }
+    
+    int minCostII(vector<vector<int>>& costs) {
+        memset(memo, -1, sizeof memo);
+        return dfs(costs, 0, -1);
+    }
+};
+

Leetcode Daily Challenge/August-2021/README.md

@@ -16,6 +16,7 @@
 | 11. | [Array of Doubled Pairs](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge-2021/614/week-2-august-8th-august-14th/3877/)                   |           [cpp](./11.%20Array%20of%20Doubled%20Pairs.cpp)            |
 | 12. | [Group Anagrams](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge-2021/614/week-2-august-8th-august-14th/3887/)                           |                 [cpp](./12.%20Group%20Anagrams.cpp)                  |
 | 13. | [Set Matrix Zeroes](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge-2021/614/week-2-august-8th-august-14th/3888/)                        |               [cpp](./13.%20Set%20Matrix%20Zeroes.cpp)               |
+|  | [Paint House II](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge-2021/615/week-3-august-15th-august-21st/3890/)                        |               [cpp](./Paint%20House%20II.cpp)               |
 | 15. | [Minimum Window Substring](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge-2021/615/week-3-august-15th-august-21st/3891/)                |           [cpp](./15.%20Minimum%20Window%20Substring.cpp)            |
 | 16. | [Range Sum Query - Immutable](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge-2021/615/week-3-august-15th-august-21st/3892/)             |        [cpp](./16.%20Range%20Sum%20Query%20-%20Immutable.cpp)        |
 | 17. | [Count Good Nodes in Binary Tree](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge-2021/615/week-3-august-15th-august-21st/3899/)         |     [cpp](./17.%20Count%20Good%20Nodes%20in%20Binary%20Tree.cpp)     |