[LeetCode]Search a 2D Matrix

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.

For example,

Consider the following matrix:

[  [1,   3,  5,  7],  [10, 11, 16, 20],  [23, 30, 34, 50]]

Given target = 3, return true.

public class Solution {public boolean searchMatrix(int[][] matrix, int target) {int row = matrix.length;int left = 0;int right = row - 1;int mid = (left + right) / 2;while (left <= right) {mid = (left + right) / 2;if (target == matrix[mid][0]) {return true;} else if (target < matrix[mid][0]) {right = mid-1;} else {left = mid+1;}}if (target < matrix[mid][0]){if(mid == 0){return false;}else{return Arrays.binarySearch(matrix[mid-1], target)>=0;}}return Arrays.binarySearch(matrix[mid], target)>=0;}}