- Difficulty: Hard
- Tags: LeetCode, Hard, Array, Binary Search, Suffix Array, Hash Function, Rolling Hash, leetcode-1923, Hash Table, O(m * nlogn), O(n), Rabin-Karp Algorithm
Problem
There is a country of n
cities numbered from 0
to n - 1
. In this country, there is a road connecting every pair of cities.
There are m
friends numbered from 0
to m - 1
who are traveling through the country. Each one of them will take a path consisting of some cities. Each path is represented by an integer array that contains the visited cities in order. The path may contain a city more than once, but the same city will not be listed consecutively.
Given an integer n
and a 2D integer array paths
where paths[i]
is an integer array representing the path of the ith
friend, return the length of the longest common subpath that is shared by every friend's path, or 0
if there is no common subpath at all.
A subpath of a path is a contiguous sequence of cities within that path.
Example 1:
Input: n = 5, paths = [[0,1,2,3,4], [2,3,4], [4,0,1,2,3]] Output: 2 Explanation: The longest common subpath is [2,3].
Example 2:
Input: n = 3, paths = [[0],[1],[2]] Output: 0 Explanation: There is no common subpath shared by the three paths.
Example 3:
Input: n = 5, paths = [[0,1,2,3,4], [4,3,2,1,0]] Output: 1 Explanation: The possible longest common subpaths are [0], [1], [2], [3], and [4]. All have a length of 1.
Constraints:
1 <= n <= 105
m == paths.length
2 <= m <= 105
sum(paths[i].length) <= 105
0 <= paths[i][j] < n
- The same city is not listed multiple times consecutively in
paths[i]
.