[BZOJ]1036: [ZJOI2008]树的统计Count

来源：互联网发布：js字符串长度格式化编辑：程序博客网时间：2024/05/16 11:22
一道树链剖分的裸题，要注意找最大值的时候ans要设得很小，我因此WA了一次。。。。。。
/**************************************************************    Problem: 1036    User: 200815147    Language: C++    Result: Accepted    Time:2792 ms    Memory:7816 kb****************************************************************/ #include<cstdio>#include<cstring>const int Q=50005;struct edge{    int y,next;}b[Q*2];int len=0,last[Q];void ins(int x,int y){    int t=++len;    b[t].y=y;b[t].next=last[x];last[x]=t;}int tot[Q],son[Q],dep[Q],ys[Q],fa[Q],top[Q];void pre_node(int x){    tot[x]=1;son[x]=0;    for(int i=last[x];i!=-1;i=b[i].next)    {        int y=b[i].y;        if(fa[x]!=y)        {            fa[y]=x;            dep[y]=dep[x]+1;            pre_node(y);            if(tot[y]>tot[son[x]]) son[x]=y;            tot[x]+=tot[y];        }    }}int z=0;void pre_edge(int x,int tp){    ys[x]=++z;top[x]=tp;    if(son[x]!=0) pre_edge(son[x],tp);    for(int i=last[x];i!=-1;i=b[i].next)    {        int y=b[i].y;        if(son[x]!=y && fa[x]!=y) pre_edge(y,y);    }}struct tree{    int l,r,Max,Sum,lc,rc;}a[Q*3];int trlen=0;void build(int l,int r){    int t=++trlen;    a[t].l=l;a[t].r=r;    if(l<r)    {        int mid=(l+r)>>1;        a[t].lc=trlen+1;build(l,mid);        a[t].rc=trlen+1;build(mid+1,r);    }}int mymax(int x,int y) {return x>y?x:y;}void change(int now,int x,int c){    if(a[now].l==a[now].r)    {        a[now].Max=a[now].Sum=c;        return;    }    int lc=a[now].lc,rc=a[now].rc,mid=(a[now].l+a[now].r)>>1;    if(x<=mid) change(lc,x,c);    else change(rc,x,c);    a[now].Sum=a[lc].Sum+a[rc].Sum;    a[now].Max=mymax(a[lc].Max,a[rc].Max);}int findmax(int now,int l,int r){    if(a[now].l==l && a[now].r==r) return a[now].Max;    int lc=a[now].lc,rc=a[now].rc,mid=(a[now].l+a[now].r)>>1;    if(r<=mid) return findmax(lc,l,r);    else if(l>mid) return findmax(rc,l,r);    else return mymax(findmax(lc,l,mid),findmax(rc,mid+1,r));}int findsum(int now,int l,int r){    if(a[now].l==l && a[now].r==r) return a[now].Sum;    int lc=a[now].lc,rc=a[now].rc,mid=(a[now].l+a[now].r)>>1;    if(r<=mid) return findsum(lc,l,r);    else if(l>mid) return findsum(rc,l,r);    else return findsum(lc,l,mid)+findsum(rc,mid+1,r);}int n,m;void solve1(int x,int y){    int tx=top[x],ty=top[y],ans=-300000;    while(tx!=ty)    {        //printf("x=%d y=%d tx=%d ty=%d\n",x,y,tx,ty);        if(dep[tx]>dep[ty])        {            int t=tx;tx=ty;ty=t;            t=x;x=y;y=t;        }        //printf("x=%d y=%d tx=%d ty=%d\n",x,y,tx,ty);        ans=mymax(ans,findmax(1,ys[ty],ys[y]));        //printf("%d %d %d\n",ys[ty],ys[y],ans);        y=fa[ty];ty=top[y];    }    if(dep[x]>dep[y]) {int t=x;x=y;y=t;}    ans=mymax(ans,findmax(1,ys[x],ys[y]));    printf("%d\n",ans);}void solve2(int x,int y){    int tx=top[x],ty=top[y],ans=0;    while(tx!=ty)    {        if(dep[tx]>dep[ty])        {            int t=tx;tx=ty;ty=t;            t=x;x=y;y=t;        }        ans+=findsum(1,ys[ty],ys[y]);        y=fa[ty];ty=top[y];    }    if(dep[x]>dep[y]) {int t=x;x=y;y=t;}    /*printf("%d %d %d %d\n",x,y,ys[x],ys[y]);    printf("%d\n",ans);*/    ans+=findsum(1,ys[x],ys[y]);    printf("%d\n",ans);}int main(){    //freopen("1.txt","w",stdout);    memset(last,-1,sizeof(last));    scanf("%d",&n);    for(int i=1;i<n;i++)    {        int x,y;        scanf("%d%d",&x,&y);        ins(x,y);ins(y,x);    }//printf("ok");    tot[0]=dep[1]=fa[1]=0;pre_node(1);    pre_edge(1,1);    build(1,n);    for(int i=1;i<=n;i++)    {        int d;        scanf("%d",&d);        change(1,ys[i],d);    }    scanf("%d",&m);//for(int i=1;i<=len;i++)    //printf("%d %d %d %d\n",i,a[i].l,a[i].r,a[i].Sum);    for(int i=1;i<=m;i++)    {        char s[10];        int x,y;        scanf("%s%d%d",s,&x,&y);        if(s[0]=='C') change(1,ys[x],y);        else if(s[1]=='M') solve1(x,y);        else solve2(x,y);    }}
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