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.

#include<vector>using std::vector;class Solution {public:bool searchMatrix(vector<vector<int> > &matrix, int target) {int n = matrix.size();if(n==0)return false;int m = matrix[0].size();int low = 0;int high = n-1;while(low <= high){int mid = (low+high)/2;if(matrix[mid][0] == target)return true;else if(matrix[mid][0] > target)high = mid-1;elselow = mid+1;}if(high < 0)return false;int loc = high;low = 0;high = m-1;while(low <= high){int mid = (low+high)/2;if(matrix[loc][mid] == target)return true;else if(matrix[loc][mid] > target)high = mid-1;elselow = mid+1;}return false;}};