Search a 2D Matrix

标签：二分查找

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<iostream>
#include<vector>
using namespace std;

bool searchMatrix(vector<vector<int> > &matrix, int target) {
	if (matrix.empty())
		return false;
	int length = matrix[0].size();
	int first = 0;
	int last = matrix.size()*length-1;

	while (first<=last)
	{
		int mid = (first + last) / 2;
		if (matrix[mid / length][mid%length] == target)
			return true;
		else if (matrix[mid / length][mid%length] < target)
			first = mid + 1;
		else
			last = mid - 1;
	}
	return false;
}

Search a 2D Matrix

标签：二分查找

原文地址：http://blog.csdn.net/li_chihang/article/details/44451331