Difference of number of distinct values on diagonals

Array Hash Table Matrix

68.4% acceptance

Feb 25, 2026

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Given a 2D grid of size m x n, you should find the matrix answer of size m x n. The cell answer[r][c] is calculated by looking at the diagonal values of the cell grid[r][c]: Let leftAbove[r][c] be the number of distinct values on the diagonal to the left and above the cell grid[r][c] not including the cell grid[r][c] itself. Let rightBelow[r][c] be the number of distinct values on the diagonal to the right and below the cell grid[r][c], not including the cell grid[r][c] itself. Then answer[r][c] = |leftAbove[r][c] - rightBelow[r][c]|.

Solution

Rust

Time O(n * m)

Space O(n * m)

LeetCode

solution.rs

impl Solution {
  pub fn difference_of_distinct_values(grid: Vec<Vec<i32>>) -> Vec<Vec<i32>> {
    let m = grid.len();
    let n = grid[0].len();
    let mut ans = vec![vec![0i32; n]; m];
    for r in 0..m {
      for c in 0..n {
        let mut set: std::collections::HashSet<i32> = std::collections::HashSet::new();
        let (mut i, mut j) = (r as i32 - 1, c as i32 - 1);
        while i >= 0 && j >= 0 {
          set.insert(grid[i as usize][j as usize]);
          i -= 1; j -= 1;
        }
        let la = set.len() as i32;
        set.clear();
        let (mut i, mut j) = (r + 1, c + 1);
        while i < m && j < n {
          set.insert(grid[i][j]);
          i += 1; j += 1;
        }
        let rb = set.len() as i32;
        ans[r][c] = (la - rb).abs();
      }
    }
    ans
  }
}