LeetCode Search a 2D Matrix

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.

Tips:

Notice user defined compare function's parameter order.

Solution:

class Solution {public:    class Comp{        public:            bool operator()(const int& target,const vector<int> &array){                return target<array[0];            }    };    bool searchMatrix(vector<vector<int> > &matrix, int target) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        vector<vector<int> >::iterator iter=upper_bound(matrix.begin(),matrix.end(),target,Comp());        if(iter==matrix.begin())            return false;        --iter;        return binary_search((*iter).begin(),(*iter).end(),target);            }};