Class Solution
- java.lang.Object
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- g1401_1500.s1466_reorder_routes_to_make_all_paths_lead_to_the_city_zero.Solution
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public class Solution extends Object
1466 - Reorder Routes to Make All Paths Lead to the City Zero.Medium
There are
n
cities numbered from0
ton - 1
andn - 1
roads such that there is only one way to travel between two different cities (this network form a tree). Last year, The ministry of transport decided to orient the roads in one direction because they are too narrow.Roads are represented by
connections
whereconnections[i] = [ai, bi]
represents a road from cityai
to citybi
.This year, there will be a big event in the capital (city
0
), and many people want to travel to this city.Your task consists of reorienting some roads such that each city can visit the city
0
. Return the minimum number of edges changed.It’s guaranteed that each city can reach city
0
after reorder.Example 1:
Input: n = 6, connections = [[0,1],[1,3],[2,3],[4,0],[4,5]]
Output: 3
Explanation: Change the direction of edges show in red such that each node can reach the node 0 (capital).
Example 2:
Input: n = 5, connections = [[1,0],[1,2],[3,2],[3,4]]
Output: 2
Explanation: Change the direction of edges show in red such that each node can reach the node 0 (capital).
Example 3:
Input: n = 3, connections = [[1,0],[2,0]]
Output: 0
Constraints:
2 <= n <= 5 * 104
connections.length == n - 1
connections[i].length == 2
0 <= ai, bi <= n - 1
ai != bi
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Constructor Summary
Constructors Constructor Description Solution()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
minReorder(int n, int[][] connections)
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