74. Search a 2D Matrix

解法一：转化为一味的向量 用模板

class Solution {
public:
    bool searchMatrix(vector<vector<int>>& matrix, int target) {
        if(matrix.empty() || matrix[0].empty()) return false;
        int rows = matrix.size();
        int cols = matrix[0].size();
        int len = rows * cols;
        int lb = -1;
        int ub = len;
        while(lb + 1 < ub){
            int mid = lb + (ub - lb)/2;
            if(matrix[mid / cols][mid % cols ] < target) lb = mid;
            else ub = mid;
        }
        if(lb + 1 == len) return false; //一定要有这句，否则超时
        if(matrix[(lb + 1) / cols][(lb + 1) % cols] == target) return true;
        return false;
    }
};