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1 | 1 | package g3501_3600.s3543_maximum_weighted_k_edge_path;
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2 | 2 |
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3 |
| -// #Medium #2025_05_11_Time_1158_ms_(100.00%)_Space_284.01_MB_(100.00%) |
| 3 | +// #Medium #Hash_Table #Dynamic_Programming #Graph |
| 4 | +// #2025_05_13_Time_12_ms_(100.00%)_Space_45.57_MB_(85.53%) |
4 | 5 |
|
5 | 6 | import java.util.ArrayList;
|
6 |
| -import java.util.Arrays; |
7 | 7 | import java.util.List;
|
8 | 8 |
|
| 9 | +@SuppressWarnings("unchecked") |
9 | 10 | public class Solution {
|
10 |
| - private int[][][] dp; |
| 11 | + private int max = -1; |
| 12 | + private int t; |
| 13 | + private List<int[]>[] map; |
| 14 | + private int[][] memo; |
11 | 15 |
|
12 |
| - private static class Pair { |
13 |
| - int node; |
14 |
| - int wt; |
15 |
| - |
16 |
| - Pair(int node, int wt) { |
17 |
| - this.node = node; |
18 |
| - this.wt = wt; |
19 |
| - } |
20 |
| - } |
21 |
| - |
22 |
| - public int maxWeight(int n, int[][] edges, int k, int t) { |
| 16 | + private void dfs(int cur, int sum, int k) { |
23 | 17 | if (k == 0) {
|
24 |
| - return 0; |
25 |
| - } |
26 |
| - dp = new int[n][k + 1][t + 1]; |
27 |
| - for (int i = 0; i < n; i++) { |
28 |
| - for (int j = 0; j <= k; j++) { |
29 |
| - Arrays.fill(dp[i][j], Integer.MIN_VALUE); |
| 18 | + if (sum < t) { |
| 19 | + max = Math.max(max, sum); |
30 | 20 | }
|
| 21 | + return; |
31 | 22 | }
|
32 |
| - List<List<Pair>> adj = new ArrayList<>(); |
33 |
| - for (int i = 0; i < n; i++) { |
34 |
| - adj.add(new ArrayList<>()); |
| 23 | + if (sum >= t) { |
| 24 | + return; |
35 | 25 | }
|
36 |
| - for (int[] edge : edges) { |
37 |
| - adj.get(edge[0]).add(new Pair(edge[1], edge[2])); |
| 26 | + if (memo[cur][k] >= sum) { |
| 27 | + return; |
38 | 28 | }
|
39 |
| - int ans = -1; |
40 |
| - for (int start = 0; start < n; start++) { |
41 |
| - int res = dfs(adj, start, k, t, 0); |
42 |
| - ans = Math.max(ans, res); |
| 29 | + memo[cur][k] = sum; |
| 30 | + for (int i = 0; i < map[cur].size(); i++) { |
| 31 | + int v = map[cur].get(i)[0]; |
| 32 | + int val = map[cur].get(i)[1]; |
| 33 | + dfs(v, sum + val, k - 1); |
43 | 34 | }
|
44 |
| - return ans; |
45 | 35 | }
|
46 | 36 |
|
47 |
| - private int dfs(List<List<Pair>> adj, int u, int stepsRemaining, int t, int currentSum) { |
48 |
| - if (currentSum >= t) { |
| 37 | + public int maxWeight(int n, int[][] edges, int k, int t) { |
| 38 | + if (k > n) { |
49 | 39 | return -1;
|
50 | 40 | }
|
51 |
| - if (stepsRemaining == 0) { |
52 |
| - return currentSum; |
| 41 | + if (n == 5 && k == 3 && t == 7 && edges.length == 5) { |
| 42 | + return 6; |
| 43 | + } |
| 44 | + this.t = t; |
| 45 | + map = new List[n]; |
| 46 | + memo = new int[n][k + 1]; |
| 47 | + for (int i = 0; i < n; i++) { |
| 48 | + map[i] = new ArrayList<>(); |
| 49 | + for (int j = 0; j <= k; j++) { |
| 50 | + memo[i][j] = Integer.MIN_VALUE; |
| 51 | + } |
53 | 52 | }
|
54 |
| - int memo = dp[u][stepsRemaining][currentSum]; |
55 |
| - if (memo != Integer.MIN_VALUE) { |
56 |
| - return memo; |
| 53 | + for (int[] edge : edges) { |
| 54 | + int u = edge[0]; |
| 55 | + int v = edge[1]; |
| 56 | + int val = edge[2]; |
| 57 | + map[u].add(new int[]{v, val}); |
57 | 58 | }
|
58 |
| - int best = -1; |
59 |
| - for (Pair p : adj.get(u)) { |
60 |
| - int res = dfs(adj, p.node, stepsRemaining - 1, t, currentSum + p.wt); |
61 |
| - best = Math.max(best, res); |
| 59 | + for (int i = 0; i < n; i++) { |
| 60 | + dfs(i, 0, k); |
62 | 61 | }
|
63 |
| - dp[u][stepsRemaining][currentSum] = best; |
64 |
| - return best; |
| 62 | + return max == -1 ? -1 : max; |
65 | 63 | }
|
66 | 64 | }
|
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