[容易]搜索二维矩阵

 1 class Solution {
 2 public:
 3     /**
 4      * @param matrix, a list of lists of integers
 5      * @param target, an integer
 6      * @return a boolean, indicate whether matrix contains target
 7      */
 8     bool searchMatrix(vector<vector<int> > &matrix, int target) {
 9         int n = matrix.size();
10         if (n == 0) {
11             return false;
12         }    
13         int m = matrix[0].size();      
14         int start = 0, end = n * m - 1;//n行m列
15         while (start + 1 < end) {
16             int mid = start + (end - start) / 2;
17             int row = mid / m;
18             int col = mid % m;
19             //从0开始计数，行和列也从0开始计数，第mid个数，在mid/m行，mid%m列
20             if (matrix[row][col] < target) {
21                 start = mid;
22             } else {
23                 end = mid;
24             }
25         }       
26         if (matrix[start / m][start % m] == target) {
27             return true;
28         }      
29         if (matrix[end / m][end % m] == target) {
30             return true;
31         }     
32         return false;
33     }
34 };