A1146 Topological Order (25 minutes | topological sort, with detailed comments, logic analysis)

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This link: https://blog.csdn.net/qq_24452475/article/details/100569928

EDITORIAL

• Ideas analysis
  • V adjacency list is stored to the FIG., The degree of each node and stored in the array indeg.
  • Each one is to judge whether the topological node traversal sequence, the current node is not 0 degree indicates the degree of all nodes is not the extension of topological columns, select a point every time you want it points minus 1
  • According to the decision of whether or not there have been the point 0 to be output if the current number i
    • flag variable to determine whether the output space
    • judge whether the variable is used to determine the topology sequence
• Simple title, storing, comparing sequence conforms topological properties
  • 25 minutes a title

Test Case

• input:
  6 8
  1 2
  1 3
  5 2
  5 4
  2 3
  2 6
  3 4
  6 4
  5
  1 5 2 3 6 4
  5 1 2 6 3 4
  5 1 2 3 6 4
  5 2 1 6 3 4
  1 2 3 4 5 6
  
  output:
  3 4
  

ac Code

• Reference links

  #include <iostream>
  #include <vector>
  using namespace std;
  
  int main()
  {
      int n, m, a, b, k, flag = 0, indeg[1010];
      vector<int> v[1010];
      scanf("%d%d", &n, &m);
  
      for(int i=0; i<m; i++)
      {
          scanf("%d %d", &a, &b);
          v[a].push_back(b);
          // 入度加1
          indeg[b]++;
      }
  
      scanf("%d", &k);
      for(int i=0; i<k; i++)
      {
          int judge = 1;
          // 复制数组
          vector<int> tin(indeg,indeg+n+1);
          for(int j=0; j<n; j++)
          {
              scanf("%d", &a);
              // 入度不为0，非拓扑排序
              if(tin[a] != 0) judge = 0;
              // 当前结点，所有子节点入度减1
              for(int it: v[a]) tin[it]--;
          }
          if(judge == 1) continue;
  
          printf("%s%d", flag == 1 ? " " : "", i);
          flag = 1;
      }
      return 0;
  }
  

Knowledge Point Summary

• Copy the array to a variable container

  int a[4]={0,10,22,3};
  
  std::vector<int> array(a, a + 4);