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7 | 7 | import java.util.Map;
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8 | 8 | import java.util.Queue;
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9 | 9 |
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10 |
| -/** |
11 |
| - * 1377. Frog Position After T Seconds |
12 |
| - * |
13 |
| - * Given an undirected tree consisting of n vertices numbered from 1 to n. |
14 |
| - * A frog starts jumping from the vertex 1. |
15 |
| - * In one second, the frog jumps from its current vertex to another unvisited vertex if they are directly connected. |
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| - * The frog can not jump back to a visited vertex. |
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| - * In case the frog can jump to several vertices it jumps randomly to one of them with the same probability, |
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| - * otherwise, when the frog can not jump to any unvisited vertex it jumps forever on the same vertex. |
19 |
| - * The edges of the undirected tree are given in the array edges, where edges[i] = [fromi, toi] means that exists an edge connecting directly the vertices fromi and toi. |
20 |
| - * Return the probability that after t seconds the frog is on the vertex target. |
21 |
| - * |
22 |
| - * Example 1: |
23 |
| - * Input: n = 7, edges = [[1,2],[1,3],[1,7],[2,4],[2,6],[3,5]], t = 2, target = 4 |
24 |
| - * Output: 0.16666666666666666 |
25 |
| - * Explanation: The figure above shows the given graph. |
26 |
| - * The frog starts at vertex 1, jumping with 1/3 probability to the vertex 2 after second 1 and |
27 |
| - * then jumping with 1/2 probability to vertex 4 after second 2. |
28 |
| - * Thus the probability for the frog is on the vertex 4 after 2 seconds is 1/3 * 1/2 = 1/6 = 0.16666666666666666. |
29 |
| - * |
30 |
| - * Example 2: |
31 |
| - * Input: n = 7, edges = [[1,2],[1,3],[1,7],[2,4],[2,6],[3,5]], t = 1, target = 7 |
32 |
| - * Output: 0.3333333333333333 |
33 |
| - * 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. |
34 |
| - * |
35 |
| - * Example 3: |
36 |
| - * Input: n = 7, edges = [[1,2],[1,3],[1,7],[2,4],[2,6],[3,5]], t = 20, target = 6 |
37 |
| - * Output: 0.16666666666666666 |
38 |
| - * |
39 |
| - * Constraints: |
40 |
| - * 1 <= n <= 100 |
41 |
| - * edges.length == n-1 |
42 |
| - * edges[i].length == 2 |
43 |
| - * 1 <= edges[i][0], edges[i][1] <= n |
44 |
| - * 1 <= t <= 50 |
45 |
| - * 1 <= target <= n |
46 |
| - * Answers within 10^-5 of the actual value will be accepted as correct. |
47 |
| - * */ |
48 | 10 | public class _1377 {
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49 | 11 | public static class Solution1 {
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50 |
| - /**credit: https://leetcode.com/problems/frog-position-after-t-seconds/discuss/532505/Java-Straightforward-BFS-Clean-code-O(N)*/ |
| 12 | + /** |
| 13 | + * credit: https://leetcode.com/problems/frog-position-after-t-seconds/discuss/532505/Java-Straightforward-BFS-Clean-code-O(N) |
| 14 | + */ |
51 | 15 | public double frogPosition(int n, int[][] edges, int t, int target) {
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52 | 16 | List<Integer>[] graph = new ArrayList[n];
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53 | 17 | for (int i = 0; i < n; i++) {
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