- Difficulty: Hard
- Tags: LeetCode, Hard, Array, Dynamic Programming, Matrix, leetcode-2435, O(m * n * k), O(n * k), DP
Problem
You are given a 0-indexed m x n
integer matrix grid
and an integer k
. You are currently at position (0, 0)
and you want to reach position (m - 1, n - 1)
moving only down or right.
Return the number of paths where the sum of the elements on the path is divisible by k
. Since the answer may be very large, return it modulo 109 + 7
.
Example 1:
Input: grid = [[5,2,4],[3,0,5],[0,7,2]], k = 3 Output: 2 Explanation: There are two paths where the sum of the elements on the path is divisible by k. The first path highlighted in red has a sum of 5 + 2 + 4 + 5 + 2 = 18 which is divisible by 3. The second path highlighted in blue has a sum of 5 + 3 + 0 + 5 + 2 = 15 which is divisible by 3.
Example 2:
Input: grid = [[0,0]], k = 5 Output: 1 Explanation: The path highlighted in red has a sum of 0 + 0 = 0 which is divisible by 5.
Example 3:
Input: grid = [[7,3,4,9],[2,3,6,2],[2,3,7,0]], k = 1 Output: 10 Explanation: Every integer is divisible by 1 so the sum of the elements on every possible path is divisible by k.
Constraints:
m == grid.length
n == grid[i].length
1 <= m, n <= 5 * 104
1 <= m * n <= 5 * 104
0 <= grid[i][j] <= 100
1 <= k <= 50