<p>Given an <code>m x n</code> integers <code>matrix</code>, return <em>the length of the longest increasing path in </em><code>matrix</code>.</p>

<p>From each cell, you can either move in four directions: left, right, up, or down. You <strong>may not</strong> move <strong>diagonally</strong> or move <strong>outside the boundary</strong> (i.e., wrap-around is not allowed).</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/01/05/grid1.jpg" style="width: 242px; height: 242px;" />
<pre>
<strong>Input:</strong> matrix = [[9,9,4],[6,6,8],[2,1,1]]
<strong>Output:</strong> 4
<strong>Explanation:</strong> The longest increasing path is <code>[1, 2, 6, 9]</code>.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/01/27/tmp-grid.jpg" style="width: 253px; height: 253px;" />
<pre>
<strong>Input:</strong> matrix = [[3,4,5],[3,2,6],[2,2,1]]
<strong>Output:</strong> 4
<strong>Explanation: </strong>The longest increasing path is <code>[3, 4, 5, 6]</code>. Moving diagonally is not allowed.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> matrix = [[1]]
<strong>Output:</strong> 1
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>m == matrix.length</code></li>
	<li><code>n == matrix[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 200</code></li>
	<li><code>0 &lt;= matrix[i][j] &lt;= 2<sup>31</sup> - 1</code></li>
</ul>

class Solution {
public:
    map<pair<int, int>, int>mp;
    vector<int>dx={1, 0, -1, 0}, dy={0, 1, 0, -1};
    vector<vector<int>>vis;
    int m, n;
    int dfs(int x, int y, vector<vector<int>>& grid){
        // vis[x][y]=1;
        int ans=1, val=0;
        if(mp.find({x, y})!=mp.end()) return mp[{x, y}];
        for(int k=0;k<4;k++){
            int kx=x+dx[k], ky=y+dy[k];
            if(kx>=0 and kx<m and ky>=0 and ky<n){
                if(grid[kx][ky]>grid[x][y]) ans=max(ans, 1+dfs(kx, ky, grid));
            }
        }
        return mp[{x, y}]=ans;
    }
    int longestIncreasingPath(vector<vector<int>>& grid) {
        m=grid.size(), n=grid[0].size();
        vis.assign(m, vector<int>(n, 0));
        int ans=1;
        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                ans=max(ans, dfs(i, j, grid));
            }
            // cout<<endl;
        }
        // cout<<mp[{2, 1}]<<endl;
        return ans;
    }
};
32278