第二题用的dfs，代码好他妈长！！！ #include<iostream> #include<string>  #include<cmath> #include<vector>  #include<algorithm> #include<queue> #include "stdlib.h" #include<limits.h> #include <iomanip> #include<map> #include <queue> #include<set> #include <sstream> using namespace std; typedef struct point       {           float x;           float y;       }Point;   bool lineIntersectSide(Point A, Point B, Point C, Point D)       {             float fC = (C.y - A.y) * (A.x - B.x) - (C.x - A.x) * (A.y - B.y);          float fD = (D.y - A.y) * (A.x - B.x) - (D.x - A.x) * (A.y - B.y);                if(fC * fD > 0){             return false;          }                             return true;     }       bool sideIntersectSide(Point A, Point B, Point C, Point D)       {           if(!lineIntersectSide(A, B, C, D)) {             return false;           }                       if(!lineIntersectSide(C, D, A, B)){             return false;           }                        return true;       } int query(int num,vector<vector<point> > qu){    queue <int > q;    int vis[qu.size()];    for(int i=0;i<qu.size();i++){        vis[i]=0;    }           int zu=1;    for(int t=0;t<qu.size();t++){        if(vis[t]==0){             vis[t]=zu;            q.push(t);    while(!q.empty()){        for(int i=0;i<qu.size();i++){            if(vis[i]==0){                bool t1=sideIntersectSide(qu[i][0],qu[i][1],qu[q.front()][0],qu[q.front()][1]);             if(t1){                 q.push(i);                 vis[i]=zu;                 //cout<<i<<endl;             }            }                      }     q.pop();    }        }             zu+=1;    }    int count=0;  num=vis[num-1];  for(int i=0;i<qu.size();i++){     if(vis[i]==num){         count++;     } }      return count;     }   int main() { int t; cin>>t; while(t--){     int n;     cin>>n; vector<vector<point> > qu;     for(int i=0;i<n;i++){         char m;         cin>>m;         if(m=='T'){             float x1,y1,x2,y2;             cin>>x1>>y1>>x2>>y2;             point p1;             p1.x=x1;             p1.y=y1;             point p2;             p2.x=x2;             p2.y=y2;             vector<point > line;             line.push_back(p1);             line.push_back(p2);             qu.push_back(line);         }         if(m=='Q'){             int w;             cin>>w;             cout<<query(w,qu)<<endl;         }     } } }