LeetCode-in-All

74. Search a 2D Matrix

Medium

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

• Integers in each row are sorted from left to right.
• The first integer of each row is greater than the last integer of the previous row.

Example 1:

Input: matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 3

Output: true

Example 2:

Input: matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 13

Output: false

Constraints:

• m == matrix.length
• n == matrix[i].length
• 1 <= m, n <= 100
• -104 <= matrix[i][j], target <= 104

Solution

class Solution {
    /**
     * @param Integer[][] $matrix
     * @param Integer $target
     * @return Boolean
     */
    public function searchMatrix($matrix, $target) {
        $endRow = count($matrix);
        $endCol = count($matrix[0]);
        $targetRow = 0;
        $result = false;
        for ($i = 0; $i < $endRow; $i++) {
            if ($matrix[$i][$endCol - 1] >= $target) {
                $targetRow = $i;
                break;
            }
        }
        for ($i = 0; $i < $endCol; $i++) {
            if ($matrix[$targetRow][$i] == $target) {
                $result = true;
                break;
            }
        }
        return $result;
    }
}

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