[LeetCode]Longest_Increasing_Path_in_a_Matrix

Author: imSunamika

Dynamic Programming/Longest_Increasing_Path_in_a_Matrix.cpp

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+// Problem Description:- Longest_Increasing_Path_in_a_Matrix
+// Link:- https://leetcode.com/problems/longest-increasing-path-in-a-matrix/
+
+
+class Solution {
+public:
+    int dp[201][201];
+    bool issafe(int i , int j, int m, int n)
+    {
+        return (i >= 0 && j >= 0 && i < m && j < n);
+    }
+    int helper(vector<vector<int>> &g, int last, int i, int j, int &m , int &n)
+    {
+        if(!issafe(i, j, m, n))return 0;
+        if(g[i][j] <= last)return 0;
+        if(dp[i][j] != -1)return dp[i][j] ;
+        int res1 = max(helper(g, g[i][j], i - 1, j , m, n), helper(g, g[i][j], i, j + 1, m, n));
+        int res2 = max(helper(g, g[i][j], i + 1, j , m, n), helper(g, g[i][j], i, j - 1, m, n));
+        dp[i][j] = 1 + max(res1, res2);
+        return dp[i][j];
+    }
+    int longestIncreasingPath(vector<vector<int>>& matrix) {
+        int m = matrix.size(), n = matrix[0].size();
+        int res = INT_MIN;
+        memset(dp, -1, sizeof(dp));
+        for(int i = 0; i < m ; i++)
+        {
+            for(int j = 0; j < n; j++)
+            {
+                res = max(res, helper(matrix, INT_MIN, i, j, m, n));
+            }
+        }
+        return res;
+    }
+};