Top 150 InterviewMedium

Longest Increasing Path In Matrix

Detailed guide and Python implementation for the 'Longest Increasing Path In Matrix' problem.

Problem Statement

Medium

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

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).

Write a function longestIncreasingPath(matrix: List[List[int]]) -> int.

Constraints
  • m == len(matrix)
  • n == len(matrix[0])
  • 1 <= m, n <= 200
  • 0 <= matrix[i][j] <= 2^31 - 1

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].

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]. Moving diagonally is not allowed.

Need a Hint?
Consider using 2D DP-specific data structures like sets or heaps.
Edge Cases to Watch
  • Empty input structures
  • Single element inputs
  • Large numerical bounds

Ready to Solve?

Open the problem in PyRun's browser-based Python editor. Your code runs fully offline — no server required.

Open in Editor

Recommended Python Resources

Expand your knowledge with related interactive tutorials, cheat sheets, and code comparisons.