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.

 

什么叫丧心病狂？m+n已经不能满足人类的欲望了，如果用二路二分，效率可达O(log m + log n)

我就不丧心病狂了。

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