317. Equal Row and Column Pairs
Medium
Sequence Hashing
Hashing
Problem
Given an n by n integer matrix grid, return the number of pairs consisting of a row and a column that contain exactly the same values in exactly the same order.
Examples
Example 1
Input: [[3,2,1],[1,7,6],[2,7,7]]
Output: 1
Example 2
Input: [[3,1,2,2],[1,4,4,5],[2,4,2,2],[2,4,2,2]]
Output: 3
Example 3
Input: [[1]]
Output: 1
Constraints
� 1 <= n <= 200
� grid.length == grid[i].length == n
� 1 <= grid[i][j] <= 100000
Hints
?? Treat each complete row as a sequence key.
?? Count how many times every row sequence occurs.
?? Construct every column sequence and look it up in the row map.
Expected Complexity
Time: O(n^2)
Space: O(n^2)
Follow-up
Can you avoid repeatedly converting entire rows and columns into strings?
Practice Notes
Attempts: 0
Time spent: 0min
Hints used: 0
JavaScript
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Case 1
Case 2
Case 3
Input
[[3,2,1],[1,7,6],[2,7,7]]Expected
1