编写一个高效的算法来判断 m x n 矩阵中，是否存在一个目标值。该矩阵具有如下特性：
示例 1:
输入:
matrix = [
[1, 3, 5, 7],
[10, 11, 16, 20],
[23, 30, 34, 50]
]
target = 3
输出: true示例 2:
输入:
matrix = [
[1, 3, 5, 7],
[10, 11, 16, 20],
[23, 30, 34, 50]
]
target = 13
输出: falseclass Solution {
public boolean searchMatrix(int[][] matrix, int target) {
if (matrix == null || matrix.length == 0 || matrix[0].length == 0)
return false;
int i = matrix.length - 1;
int j = 0;
while (i >= 0 && j < matrix[0].length) {
if (matrix[i][j] == target)
return true;
else if (matrix[i][j] < target)
j++;
else
i--;
}
return false;
}
}原文：https://www.cnblogs.com/WeichengDDD/p/10815886.html