49 lines
1.3 KiB
C++
49 lines
1.3 KiB
C++
#include <vector>
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#include <functional>
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#include <cstdio>
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/**
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* 329. Longest Increasing Path in a Matrix
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* Given an m x n integers matrix, return the length of the longest increasing path in matrix.
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* From each cell, you can either move in four directions: left, right, up, or down. You may not move diagonally or move outside the boundary (i.e., wrap-around is not allowed).
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*/
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class Solution {
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private:
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inline static int dX[] = {0, 1, 0, -1};
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inline static int dY[] = {1, 0, -1, 0};
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public:
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static int longestIncreasingPath(const std::vector<std::vector<int>>& matrix) {
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const int m = matrix.size(), n = matrix.front().size();
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int* dp = new int[m * n]{};
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std::function<int(int)> d = [&](int id) {
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if (dp[id])
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return dp[id];
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const int x = id / n, y = id % n;
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// 4 directions
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int ans = 1;
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for (int i = 0; i < 4; ++i) {
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if (x + dX[i] < 0 || x + dX[i] >= m || y + dY[i] < 0 || y + dY[i] >= n || matrix[x + dX[i]][y + dY[i]] <= matrix[x][y])
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continue;
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ans = std::max(ans, 1 + d((x + dX[i]) * n + (y + dY[i])));
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}
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return dp[id] = ans;
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};
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int ret = 0;
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for (int i = 0; i < m * n; ++i)
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ret = std::max(ret, d(i));
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delete[] dp;
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return ret;
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}
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};
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int main() {
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std::printf("%d\n", Solution::longestIncreasingPath({{9,9,4},{6,6,8},{2,1,1}}));
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return 0;
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}
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