Search a 2D Matrix
Write an efficient algorithm that searches for a value in anm 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
.
class Solution { public: bool searchMatrix(vector<vector<int> > &matrix, int target) { if (matrix.empty()) return false; int m = matrix.size(); int n = matrix[0].size(); int first = 0; int last = m*n; while (first < last) { int mid = first + (last - first) /2; int value = matrix[mid /n][mid %n]; if(value == target) return true; else if (value < target) first = mid +1; else last = mid; } return false; } };
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