[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

.

解题思路：

二分，递归。

class Solution {
public:
int m = 0, n = 0;
vector<vector<int>> data;
bool search(int left, int right, int target)
{
int mid = (right + left) / 2;
if(right - left == 1) return target == data[left / n][left % n];
else return search(left, mid, target) || search(mid, right, target);
}
bool searchMatrix(vector<vector<int> > &matrix, int target) {
// IMPORTANT: Please reset any member data you declared, as
// the same Solution instance will be reused for each test case.
if(matrix.size() == 0) return false;
data = matrix;
m = matrix.size(), n = matrix[0].size();
return search(0, m * n, target);
}
};