Class Solution
- java.lang.Object
-
- g1301_1400.s1377_frog_position_after_t_seconds.Solution
-
public class Solution extends Object
1377 - Frog Position After T Seconds.Hard
Given an undirected tree consisting of
n
vertices numbered from1
ton
. A frog starts jumping from vertex 1. In one second, the frog jumps from its current vertex to another unvisited vertex if they are directly connected. The frog can not jump back to a visited vertex. In case the frog can jump to several vertices, it jumps randomly to one of them with the same probability. Otherwise, when the frog can not jump to any unvisited vertex, it jumps forever on the same vertex.The edges of the undirected tree are given in the array
edges
, whereedges[i] = [ai, bi]
means that exists an edge connecting the verticesai
andbi
.Return the probability that after
t
seconds the frog is on the vertextarget
. Answers within10-5
of the actual answer will be accepted.Example 1:
Input: n = 7, edges = [[1,2],[1,3],[1,7],[2,4],[2,6],[3,5]], t = 2, target = 4
Output: 0.16666666666666666
Explanation: The figure above shows the given graph. The frog starts at vertex 1, jumping with 1/3 probability to the vertex 2 after second 1 and then jumping with 1/2 probability to vertex 4 after second 2. Thus the probability for the frog is on the vertex 4 after 2 seconds is 1/3 * 1/2 = 1/6 = 0.16666666666666666.
Example 2:
Input: n = 7, edges = [[1,2],[1,3],[1,7],[2,4],[2,6],[3,5]], t = 1, target = 7
Output: 0.3333333333333333
Explanation: The figure above shows the given graph. The frog starts at vertex 1, jumping with 1/3 = 0.3333333333333333 probability to the vertex 7 after second 1.
Constraints:
1 <= n <= 100
edges.length == n - 1
edges[i].length == 2
1 <= ai, bi <= n
1 <= t <= 50
1 <= target <= n
-
-
Constructor Summary
Constructors Constructor Description Solution()
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description double
frogPosition(int n, int[][] edges, int t, int target)
-