[POJ3710] Christmas Game (Game tree Delete edge game) __ the puzzle

Topic Description

Transmission Door
There are n local unicom map. Harry and Sally take turns deleting an edge from the picture, and the part that does not connect to the root node is removed. Sally is a tempo. The graph is obtained by adding some edges from the underlying tree. All formed loops are guaranteed to not share edges, and only have a common point with the underlying tree. Who can't move who loses. Solving

In game theory, a typical tree pruning game and the method of dealing with the ring.
Because there are 2 rings of the size, pay special attention when dealing with them. I just because of this problem pit for half a day, wrote several versions of the code ...
DFS and Tarjan can do code .

#include <iostream> #include <cstring> #include <cstdio> using namespace std;
#define N-T,n,m,x,y,top,ans int;
int tot,point[n],nxt[n*10],v[n*10];

int sg[n],stack[n],vis[n];
    void Clear () {n=m=x=y=top=0;
    Tot=0;memset (point) (point,0,sizeof);
memset (sg,0,sizeof (SG)); memset (vis,-1,sizeof (VIS)); } void Add (int x,int y) {++tot; nxt[tot]=point[x]; point[x]=tot; v[tot]=y;} void dfs (int x,int fa) {stack[++top
    ]=x;vis[x]=1;
    BOOL Flag=false;
            for (int i=point[x];i;i=nxt[i]) {if (V[i]==fa&&!flag) {flag=true;
        Continue
            } if (vis[v[i]]==1) {int now=stack[top],cnt=1;
                while (Now!=v[i]) {cnt++;
                vis[now]=0;
            Now=stack[--top];
        } if (cnt%2) sg[v[i]]^=1;
            else if (vis[v[i]]==-1) {DFS (v[i],x); if (Vis[v[i]]) sg[x]^= (Sg[v[i])+1);
} if (vis[x])--top;
        int main () {while (~SCANF ("%d", &t)) {ans=0;
            while (t--) {clear ();
            scanf ("%d%d", &n,&m);
                for (int i=1;i<=m;++i) {scanf ("%d%d", &x,&y);
            Add (x,y); add (y,x);
            DFS (1,0);
        ANS^=SG[1];
        if (ans) puts ("Sally");
    Else puts ("Harry"); }
}

Summary

① don't forget to leave the stack