Length of Longest V-Shaped Diagonal Segment
You are given a 2D integer matrix grid of size n x m, where each element is either 0, 1, or 2.
A V-shaped diagonal segment is defined as follows:
- The segment starts with
1. - The subsequent elements follow this infinite sequence:
2, 0, 2, 0, .... - The segment starts along a diagonal direction:
- top-left to bottom-right,
- bottom-right to top-left,
- top-right to bottom-left,
- bottom-left to top-right.
- The segment continues the sequence in the same diagonal direction.
- The segment makes at most one clockwise 90-degree turn to another diagonal direction while maintaining the sequence.
Return the length of the longest V-shaped diagonal segment. If no valid segment exists, return 0.
Example 1
2 2 1 2 2 2 0 2 2 0 2 0 1 1 0 1 0 2 2 2 2 0 0 2 2
Input
grid = [[2,2,1,2,2],[2,0,2,2,0],[2,0,1,1,0],[1,0,2,2,2],[2,0,0,2,2]]Output
5The longest V-shaped diagonal segment has a length of 5 and follows coordinates (0,2) → (1,3) → (2,4), turns clockwise at (2,4), and continues as (3,3) → (4,2).
Example 2
2 2 2 2 2 2 0 2 2 0 2 0 1 1 0 1 0 2 2 2 2 0 0 2 2
Input
grid = [[2,2,2,2,2],[2,0,2,2,0],[2,0,1,1,0],[1,0,2,2,2],[2,0,0,2,2]]Output
4The longest V-shaped diagonal segment has a length of 4 and follows coordinates (2,3) → (3,2), turns clockwise at (3,2), and continues as (2,1) → (1,0).
Constraints
- n == grid.length
- m == grid[i].length
- 1 <= n, m <= 500
- grid[i][j] is either 0, 1 or 2.