【NOIP2017模拟8.8】Trip

  1 #include<iostream>
  2 #include<cstring>
  3 #include<cstdio>
  4 #define N 3000002
  5 using namespace std;
  6 int n,m,t,zhan[N],len,num,ans[N],f[N],u,v,head[N],root,visit[N];
  7 struct data1{
  8     int l,r,p,v,lnum,rnum;
  9     void init(){
 10         l=0,r=0,p=0,v=0,lnum=0,rnum=0;
 11     }
 12 }tree[N];
 13 struct data2{
 14     int next,to,sign;
 15 }line[N];
 16 int read()
 17 {
 18        int x=0,sig=1;
 19        char c;
 20        for (c=getchar();c<‘0‘ || c>‘9‘;c=getchar()) if (c==‘-‘) sig=-1;
 21        for (;c>=‘0‘ && c<=‘9‘;c=getchar()) x=x*10+c-48;
 22        return x*sig;
 23 }
 24 void write(int x)
 25 {
 26        if (!x) putchar(‘0‘);else
 27        {
 28               char s[10];
 29               int i,j=0;
 30               for (;x>0;x/=10) s[j++]=x%10;
 31               for (i=j-1;i>=0;i--) putchar(s[i]+48);
 32        }
 33        putchar(‘\n‘);
 34 }
 35 void add(int u,int v){
 36     num++;
 37     line[num].next=head[u];
 38     line[num].to=v;
 39     line[num].sign=num;
 40     head[u]=num;
 41     num++;
 42     line[num].next=head[v];
 43     line[num].to=u;
 44     line[num].sign=num;
 45     head[v]=num;
 46 }
 47 int build(){     //建笛卡尔树 
 48     len=1;
 49     zhan[1]=1;
 50     for (int i=2;i<=n;i++){
 51         while ((len>0)&&(tree[zhan[len]].v<tree[i].v)) len--;
 52         if (len){
 53             tree[i].p=zhan[len];
 54             tree[tree[zhan[len]].r].p=i;
 55             tree[i].l=tree[zhan[len]].r;
 56             tree[zhan[len]].r=i;
 57         }
 58         else {
 59             tree[zhan[1]].p=i;
 60             tree[i].l=zhan[1];
 61         }
 62         zhan[++len]=i;    
 63     }
 64     return zhan[1];
 65 }
 66 int find(int x){
 67     if (f[x]==x) return x;
 68     f[x]=find(f[x]);
 69     return f[x];
 70 }
 71 void tarjan(int x,int ln,int rn){   //Tarjan求LCA 
 72     f[x]=x;
 73     visit[x]=1;
 74     tree[x].lnum=ln;
 75     tree[x].rnum=rn;
 76     if (tree[x].l) {
 77         tarjan(tree[x].l,ln+1,rn);
 78         f[tree[x].l]=x;
 79     }
 80     if (tree[x].r) {
 81         tarjan(tree[x].r,ln,rn+1);
 82         f[tree[x].r]=x;
 83     }
 84     int v=0,e=0;
 85     for (int i=head[x];i!=0;i=line[i].next){
 86         v=line[i].to;
 87         if (visit[v]){e=find(v);
 88         if (line[i].sign&1) ans[(line[i].sign+1)/2]=tree[x].lnum-tree[e].lnum+tree[v].rnum-tree[e].rnum+1;
 89         else ans[line[i].sign/2]=tree[v].lnum-tree[e].lnum+tree[x].rnum-tree[e].rnum+1;
 90         }
 91     }
 92 }
 93 int main(){
 94     freopen("trip.in","r",stdin);
 95     freopen("trip.out","w",stdout);    
 96     memset(visit,0,sizeof(visit));
 97     n=read();
 98     m=read();
 99     for (int i=1;i<=n;i++){
100         tree[i].init();
101         tree[i].v=read();
102     }
103     root=build();
104     num=0;
105     for (int i=1;i<=m;i++){
106         u=read();
107         v=read();
108         add(u,v);
109     }
110     tarjan(root,0,0);
111     for (int i=1;i<=m;i++)
112      write(ans[i]);
113     return 0;
114 }