解题思路：

从左下角开始，根据条件删除行和列。

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