LeetCode-in-All

240. Search a 2D Matrix II

Medium

Write an efficient algorithm that searches for a value target in an m x n integer matrix matrix. This matrix has the following properties:

• Integers in each row are sorted in ascending from left to right.
• Integers in each column are sorted in ascending from top to bottom.

Example 1:

Input: matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 5

Output: true

Example 2:

Input: matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 20

Output: false

Constraints:

• m == matrix.length
• n == matrix[i].length
• 1 <= n, m <= 300
• -109 <= matrix[i][j] <= 109
• All the integers in each row are sorted in ascending order.
• All the integers in each column are sorted in ascending order.
• -109 <= target <= 109

Solution

impl Solution {
    pub fn search_matrix(matrix: Vec<Vec<i32>>, target: i32) -> bool {
        if matrix.is_empty() || matrix[0].is_empty() {
            return false;
        }

        let mut r = 0;
        let mut c = matrix[0].len() as i32 - 1;
        
        while r < matrix.len() && c >= 0 {
            let val = matrix[r][c as usize];
            if val == target {
                return true;
            } else if val > target {
                c -= 1;
            } else {
                r += 1;
            }
        }
        
        false
    }
}

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