Nc29 search in two-dimensional array

describe
In a two-dimensional array array in （ Each one-dimensional array has the same length ）, Each row is sorted in ascending order from left to right , Each column is sorted in ascending order from top to bottom . Please complete a function , Enter such a two-dimensional array and an integer , Determine whether the array contains the integer .
[
[1,2,8,9],
[2,4,9,12],
[4,7,10,13],
[6,8,11,15]
]
Given target = 7, return true.

Given target = 3, return false.

Advanced ： Spatial complexity O(1)O(1) , Time complexity O(n+m)O(n+m)
Example 1

 Input ：
7,[[1,2,8,9],[2,4,9,12],[4,7,10,13],[6,8,11,15]]
 Return value ：
true
 explain ：
 There is 7, return true   

Example 2

 Input ：
1,[[2]]
 Return value ：
false

Example 3

 Input ：
3,[[1,2,8,9],[2,4,9,12],[4,7,10,13],[6,8,11,15]]
 Return value ：
false
 explain ：
 non-existent 3, return false   

Code：

class Solution {
    
public:
    bool Find(int target, vector<vector<int> > array) {
    
        for(int i=0;i<array.size();i++)
        {
    
            vector<int> subvec=array[i];
            for(int j=0;j<subvec.size();j++)
            {
    
                vector<int>::iterator it=find(subvec.begin(),subvec.end(),target);
                if(it!=subvec.end())
                    return true;
            }
        }
        return false;
    }
};