_240.java

package com.fishercoder.solutions;

/**
 * 240. Search a 2D Matrix II
 *
 * 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 in ascending from left to right.
 Integers in each column are sorted in ascending from top to bottom.
 For example,

 Consider the following 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]
 ]
 Given target = 5, return true.

 Given target = 20, return false.
 */
public class _240 {

    public static class Solution1 {
        public boolean searchMatrix(int[][] matrix, int target) {
            if (matrix == null || matrix.length == 0) {
                return false;
            }
            int m = matrix.length;
            int n = matrix[0].length;
            int x = 0;
            int y = n - 1;
            while (x < m && y >= 0) {
                if (target == matrix[x][y]) {
                    return true;
                } else if (target > matrix[x][y]) {
                    x++;
                } else {
                    y--;
                }
            }
            return false;
        }
    }

}