LeetCode Link: 74. Search a 2D Matrix
Language: C#
Problem Statement
You are given an m x n integer matrix matrix with the following two properties:
Each row is sorted in non-decreasing order. The first integer of each row is greater than the last integer of the previous row. Given an integer target, return true if target is in matrix or false otherwise.
You must write a solution in O(log(m * n)) time complexity.
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.length
- n == matrix[i].length
- 1 <= m, n <= 100
- -104 <= matrix[i][j], target <= 104
Solution
public class Solution
{
public bool SearchMatrix(int[][] matrix, int target)
{
int i=0;
if (matrix.Length == 0 || matrix[0].Length == 0 || matrix[0][0] > target)
{
return false;
}
while (i < matrix.Length && matrix[i][0] < target && matrix[i][matrix[i].Length - 1] < target)
{
i++;
}
return (i == matrix.Length)
? false
: BinarySearch(matrix[i], target);
}
private bool BinarySearch(int[] nums, int target)
{
int l = 0, h = nums.Length;
while (l <= h)
{
var m = (l + h)/2;
if (nums[m] == target)
{
return true;
}
if (target > nums[m])
{
l = m + 1;
}
else
{
h = m - 1;
}
}
return false;
}
}
Complexity
Time Complexity: O(MlogN)
Space Complexity: O(1)