URAL-1736-Chinese Hockey

Question: n teams play a game. Each two teams only play one game. The team wins three points in the specified time and loses 0 points. If the team hits the overtime match, the team wins two points, if the score is 1 point, the final total score of n teams is displayed. If this result is possible, the score of each team in each game is displayed, otherwise, the output is "INCORRECT" (2 <= n <= 200 ). --> After the game, the younger brother said this was a big online stream problem ~ Set a super source node s and a super collection point t. Each team has one node, and each game has one node. From s to each game, each game has one edge, the capacity is 3. From each competition to the competition, the two participating teams each have one edge, and the capacity is 3. Finally, each team connects one edge to t, capacity is the corresponding score. Then, run the maximum stream once. If the maximum stream is 3 * n * (n-1)/2, the score is correct. Then, the corresponding data is output based on the traffic of each game, otherwise, the score is incorrect.

#include <cstdio>  #include <cstring>  #include <vector>  #include <queue>    using namespace std;    const int maxv = 200 + 10;  const int maxn = 40000 + 10;  const int INF = 0x3f3f3f3f;    int a[maxv], vs[maxv][maxv];    struct Edge{      int u;      int v;      int cap;      int flow;  };    struct Dinic{      int n, m, s, t;      vector<Edge> edges;      vector<int> G[maxn];      bool vis[maxn];      int d[maxn];      int cur[maxn];        int addEdge(int uu, int vv, int cap){          edges.push_back((Edge){uu, vv, cap, 0});          edges.push_back((Edge){vv, uu, 0, 0});          m = edges.size();          G[uu].push_back(m-2);          G[vv].push_back(m-1);          return m-2;      }        bool bfs(){          memset(vis, 0, sizeof(vis));          queue<int> qu;          qu.push(s);          d[s] = 0;          vis[s] = 1;          while(!qu.empty()){              int x = qu.front(); qu.pop();              int si = G[x].size();              for(int i = 0; i < si; i++){                  Edge& e = edges[G[x][i]];                  if(!vis[e.v] && e.cap > e.flow){                      vis[e.v] = 1;                      d[e.v] = d[x] + 1;                      qu.push(e.v);                  }              }          }          return vis[t];      }        int dfs(int x, int a){          if(x == t || a == 0) return a;          int flow = 0, f;          int si = G[x].size();          for(int& i = cur[x]; i < si; i++){              Edge& e = edges[G[x][i]];              if(d[x] + 1 == d[e.v] && (f = dfs(e.v, min(a, e.cap-e.flow))) > 0){                  e.flow += f;                  edges[G[x][i]^1].flow -= f;                  flow += f;                  a -= f;                  if(a == 0) break;              }          }          return flow;      }        int Maxflow(int s, int t){          this->s = s;          this->t = t;          int flow = 0;          while(bfs()){              memset(cur, 0, sizeof(cur));              flow += dfs(s, INF);          }          return flow;      }  };    int main()  {      int n;      while(scanf("%d", &n) == 1){          Dinic din;          int t = n + n * (n-1) / 2 + 1;          for(int i = 1; i <= n; i++){              scanf("%d", &a[i]);              din.addEdge(i, t, a[i]);          }          for(int i = 1, k = n+1; i <= n; i++)              for(int j = i+1; j <= n; j++, k++){                  vs[i][j] = din.addEdge(0, k, 3);                  din.addEdge(k, i, 3);                  din.addEdge(k, j, 3);              }          if(din.Maxflow(0, t) == 3 * n * (n-1) / 2){              puts("CORRECT");              for(int i = 1; i <= n; i++)                  for(int j = i+1; j <= n; j++){                      int L = din.edges[vs[i][j]+2].flow;                      int R = din.edges[vs[i][j]+4].flow;                      if(L == 3 && R == 0) printf("%d > %d\n", i, j);                      else if(L == 0 && R == 3) printf("%d < %d\n", i, j);                      else if(L == 2 && R == 1) printf("%d >= %d\n", i, j);                      else printf("%d <= %d\n", i, j);                  }          }          else puts("INCORRECT");      }