0240 - Search a 2D Matrix II

0240 - Search a 2D Matrix II

Write an efficient algorithm that searches for a target value in an m x n integer matrix. The 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.

Examples

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

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

Java Solution

class Solution {
    public boolean searchMatrix(int[][] matrix, int target) {
        int rowIndex = 0;
        int columnIndex = matrix[0].length-1;
        
        while(rowIndex <= matrix.length-1 && columnIndex >= 0) {
            if(matrix[rowIndex][columnIndex] == target) return true;
            else if(matrix[rowIndex][columnIndex] > target) columnIndex--;
            else if(matrix[rowIndex][columnIndex] < target) rowIndex++;
        }
        
        return false;
    }
}