Longest Increasing Path in a Matrix

Hard~35 min

Given an m x n integers matrix, return the length of the longest increasing path in the matrix.

From each cell, you can either move in four directions: left, right, up, or down. You may not move diagonally or move outside of the boundary.

Examples

Example 1
Input: matrix = [[9,9,4],[6,6,8],[2,1,1]]
Output: 4
Explanation: The longest increasing path is [1, 2, 6, 9]. Length = 4.
Example 2
Input: matrix = [[3,4,5],[3,2,6],[2,2,1]]
Output: 4
Explanation: The longest increasing path is [3, 4, 5, 6]. Length = 4.
Example 3
Input: matrix = [[1]]
Output: 1
Explanation: A single cell forms a path of length 1.

Constraints

  • m == matrix.length
  • n == matrix[i].length
  • 1 <= m, n <= 200
  • 0 <= matrix[i][j] <= 2^31 - 1
  • Expected time complexity: O(m × n)
Code
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Output

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