240. Search a 2D Matrix II

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本文介绍了一种高效的算法，用于在一个特殊排序的m×n矩阵中搜索特定值。该矩阵的每一行从左到右递增排序，每一列从上到下递增排序。文章提供了具体的例子和实现代码。

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题目：

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 in ascending from left to right.
Integers in each column are sorted in ascending from top to bottom.

For example,

Consider the following matrix:

[
  [1,   4,  7, 11, 15],
  [2,   5,  8, 12, 19],
  [3,   6,  9, 16, 22],
  [10, 13, 14, 17, 24],
  [18, 21, 23, 26, 30]
]

Given target = 5, return true.

Given target = 20, return false.

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 in ascending from left to right.
Integers in each column are sorted in ascending from top to bottom.

For example,

Consider the following matrix:

[
  [1,   4,  7, 11, 15],
  [2,   5,  8, 12, 19],
  [3,   6,  9, 16, 22],
  [10, 13, 14, 17, 24],
  [18, 21, 23, 26, 30]
]

Given target = 5, return true.

Given target = 20, return false.

翻译：

编写一个搜索m×n矩阵中的值的有效算法。该矩阵具有以下属性：

每行中的整数按从左到右的顺序进行排序。
每列中的整数按照从上到下的顺序进行排序。
例如，

考虑以下矩阵：

[
[1,4,7,11,15]，
[2，5，8，12，19]，
[3，6，9，16，22]，
[10，13，14，17，24]，
[18,21,23,26,30]
]
给定target = 5，返回true。

给定目标= 20，返回false。

解题代码：

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

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

class Solution {
public:
    bool searchMatrix(vector<vector<int> >& matrix, int target) {
    	int m = matrix.size();
    	if(m == 0) return false;
    	int n = matrix[0].size();
    	int i = 0, j = n -1;
    	while(i < m && j >= 0) {
    		if(matrix[i][j] == target) return true;
    		else if(matrix[i][j] > target) {
    			j--;
			} else i++;
		}
		return false;
    }
};

int main() {
	int arr[4][5] = {
		{1,   4,  7, 11, 15},
 		{2,   5,  8, 12, 19},
   		{3,   6,  9, 16, 22},
   		{10, 13, 14, 17, 24},
  	//	{18, 21, 23, 26, 30}
		  };
	vector<vector<int> > v;
	for(int i = 0; i < 4 ;i++) {
		v.push_back(vector<int> ( arr[i],arr[i]+5) );
	}
	 Solution s;
	 cout << s.searchMatrix(v,5) << " " << s.searchMatrix(v,20)<<endl;
}

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