10531053. Path of Equal Weight (30)

Given a non-empty tree with root R, and with weight W_i assigned to each tree node T_i. The weight of a path from R to L is defined to be the sum of the weights of all the nodes along the path from R to any leaf node L.

Now given any weighted tree, you are supposed to find all the paths with their weights equal to a given number. For example, let’s consider the tree showed in Figure 1: for each node, the upper number is the node ID which is a two-digit number, and the lower number is the weight of that node. Suppose that the given number is 24, then there exists 4 different paths which have the same given weight: {10 5 2 7}, {10 4 10}, {10 3 3 6 2} and {10 3 3 6 2}, which correspond to the red edges in Figure 1.

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Figure 1

Input Specification:

Each input file contains one test case. Each case starts with a line containing 0 < N <= 100, the number of nodes in a tree, M (< N), the number of non-leaf nodes, and 0 < S < 2³⁰, the given weight number. The next line contains N positive numbers where W_i (<1000) corresponds to the tree node T_i. Then M lines follow, each in the format:

ID K ID[1] ID[2] ... ID[K]

where ID is a two-digit number representing a given non-leaf node, K is the number of its children, followed by a sequence of two-digit ID’s of its children. For the sake of simplicity, let us fix the root ID to be 00.

Output Specification:

For each test case, print all the paths with weight S in non-increasing order. Each path occupies a line with printed weights from the root to the leaf in order. All the numbers must be separated by a space with no extra space at the end of the line.

Note: sequence {A₁, A₂, …, A_n} is said to be greater than sequence {B₁, B₂, …, B_m} if there exists 1 <= k < min{n, m} such that A_i = B_i for i=1, … k, and A_k+1 > B_k+1.

Sample Input:
20 9 24
10 2 4 3 5 10 2 18 9 7 2 2 1 3 12 1 8 6 2 2
00 4 01 02 03 04
02 1 05
04 2 06 07
03 3 11 12 13
06 1 09
07 2 08 10
16 1 15
13 3 14 16 17
17 2 18 19

Sample Output:
10 5 2 7
10 4 10
10 3 3 6 2
10 3 3 6 2

数据结构太复杂了，28分，实在找不出错误

#include <iostream>  #include <cstdio>  #include <algorithm>  #include <vector>  #include <map>  using namespace std;  int N, M, sum, f, n, c;  int weight[102];  map<int, vector<int> > adjlist;  vector<int> trace;  bool cmp(int a, int b) {      return weight[a] > weight[b];  }  void dfs(int start, int cur_sum) {      if(cur_sum > sum)   return;      if(sum == cur_sum && adjlist[start].empty()) {          for(int i=0; i<trace.size()-1; i++)              printf("%d ", weight[trace[i]]);          printf("%d\n", weight[trace[trace.size()-1]]);      }      // may throw exception      for(int i=0; i<adjlist[start].size(); i++) {          int next = adjlist[start][i];          trace.push_back(next);          dfs(next, cur_sum + weight[next]);          trace.pop_back();      }  }  int main()  {      scanf("%d %d %d", &N, &M, &sum);      for(int i=0; i<N; i++)          scanf("%d", &weight[i]);      for(int i=0; i<M; i++) {          scanf("%d %d", &f, &n);          vector<int> v;          for(int j=0; j<n; j++) {              scanf("%d", &c);              adjlist[f].push_back(c);          }          sort(adjlist[f].begin(), adjlist[f].end(), cmp);      }      trace.push_back(0);      dfs(0, weight[0]);      return 0;  }