Leetcode 74

class Solution {
public:
    bool searchMatrix(vector<vector<int>>& matrix, int target) {
        int m = matrix.size();
        if(!m) return false;
        int n = matrix[].size();
        if(!n) return false;
        if(target < matrix[][] || target > matrix[m-][n-]) return false;
        int a = m-;
        for(int i=;i < m;i++){
            if(target < matrix[i][]){
                a = i-;
                break;
            }
        }
        int j = ;
        int k = n-;
        while(j <= k){
            int mid = (j+k)/;
            if(matrix[a][mid] < target){j = mid+;}
            else if(matrix[a][mid] > target){k = mid - ;}
            else{
                return true;
            }
        }
        return false;
    }
};