hardLeetCode#memoization#dfs#dag

Longest Increasing Path in a Matrix

Find the longest strictly increasing path moving between orthogonal neighbors.

The Runtime Theory TeamSeptember 25, 202625 min read

Solve it

Solving happens on the judge — come back and mark it done

Sample cases

inmatrix=[[9,9,4],[6,6,8],[2,1,1]]

out4

inmatrix=[[3,4,5],[3,2,6],[2,2,1]]

out4

inmatrix=[[1]]

out1

Find the longest strictly increasing path moving between orthogonal neighbors.

A good solution should

State the invariant or decision rule that makes the approach correct.
Explain time and space costs in terms of input size and required output.
Handle empty, minimal, duplicate, and boundary-shaped inputs.

Reasoning prompt

Memoize the best path starting at each cell. Strictly increasing edges form a DAG, so completed subproblems need no shared visited flag.

Use the linked judge for the canonical challenge. The examples above are compact TRT checks; create additional tests around the boundary most likely to break your invariant.

One dispatch a week

The trace behind each problem, the tradeoff that explains it, and one technical dispatch per week — no noise.

One technical dispatch per week. No noise.

Not started

A good solution should

Reasoning prompt

More practice in this topic

One dispatch a week