Search a 2D Matrix
Problem Statement - link #
Write an efficient algorithm that searches for a value in an m 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.
Examples #
Example 1:
Input: matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 3
Output: true
Example 2:
Input: matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 13
Output: false
Constraints #
m == matrix.lengthn == matrix[i].length1 <= m, n <= 100-10^4 <= matrix[i][j], target <= 10^4
Solutions #
class Solution {
public:
bool searchMatrix(vector<vector<int>>& matrix, int target) {
int rows = matrix.size();
int cols = matrix[0].size();
int l = 0;
int r = rows*cols - 1;
while(l<=r){
int mid = (l+r)>>1;
int midr = mid/cols;
int midc = mid%cols;
if(matrix[midr][midc]==target) return true;
else if(matrix[midr][midc]>target) r=mid-1;
else l=mid+1;
}
return false;
}
};