LeetCode101: 74. Search a 2D Matrix

class Solution {
public:
	bool searchMatrix(vector<vector<int> > &matrix, int target) {
		int n = matrix.size();
		int m = matrix[0].size();
		int l = 0, r = m * n - 1;
		while (l != r){
			int mid = l + (r - l) / 2;
			if (matrix[mid / m][mid % m] < target)
				l = mid + 1;
			else
				r = mid;
		}
		return matrix[r / m][r % m] == target;
	}
};