[BZOJ2819]Nim（树链剖分）

题目描述

传送门

题解

为了学手写栈刷了一道水题。
线段树+树链剖分维护区间xor和

代码

递归

#include<iostream>#include<cstring>#include<cstdio>using namespace std;const int max_n=5e5+5;const int max_m=max_n*2;const int max_tree=max_n*4;int n,m,x,y,u,t,ans,q,N,a[max_n];int tot,point[max_n],nxt[max_m],v[max_m];int size[max_n],h[max_n],father[max_n],son[max_n],top[max_n],num[max_n],val[max_n];int tree[max_tree];inline void addedge(int x,int y){    ++tot; nxt[tot]=point[x]; point[x]=tot; v[tot]=y;    ++tot; nxt[tot]=point[y]; point[y]=tot; v[tot]=x;}inline void dfs_1(int x,int fa,int dep){    size[x]=1; h[x]=dep; father[x]=fa;    int maxson=0;    for (int i=point[x];i;i=nxt[i])        if (v[i]!=fa)        {            dfs_1(v[i],x,dep+1);            size[x]+=size[v[i]];            if (size[v[i]]>maxson)            {                maxson=size[v[i]];                son[x]=v[i];            }        }}inline void dfs_2(int x,int fa){    if (son[fa]!=x) top[x]=x;    else top[x]=top[fa];    num[x]=++N; val[N]=a[x];    if (son[x]) dfs_2(son[x],x);    for (int i=point[x];i;i=nxt[i])        if (v[i]!=fa&&v[i]!=son[x])            dfs_2(v[i],x);}inline void update(int now){    tree[now]=tree[now<<1]^tree[now<<1|1];}inline void build(int now,int l,int r){    int mid=(l+r)>>1;    if (l==r)    {        tree[now]=val[l];        return;    }    build(now<<1,l,mid);    build(now<<1|1,mid+1,r);    update(now);}inline void point_change(int now,int l,int r,int x,int v){    int mid=(l+r)>>1;    if (l==r)    {        tree[now]=v;        return;    }    if (x<=mid)        point_change(now<<1,l,mid,x,v);    else        point_change(now<<1|1,mid+1,r,x,v);    update(now);}inline int query(int now,int l,int r,int lrange,int rrange){    int mid=(l+r)>>1,ans=0;    if (lrange<=l&&r<=rrange)        return tree[now];    if (lrange<=mid)        ans^=query(now<<1,l,mid,lrange,rrange);    if (mid+1<=rrange)        ans^=query(now<<1|1,mid+1,r,lrange,rrange);    return ans;}int main(){    scanf("%d",&n);    for (int i=1;i<=n;++i) scanf("%d",&a[i]);    for (int i=1;i<n;++i)    {        scanf("%d%d",&x,&y);        addedge(x,y);    }    dfs_1(1,0,1);    dfs_2(1,0);    build(1,1,N);    scanf("%d",&q);    for (int i=1;i<=q;++i)    {        char opt=getchar();        while (opt!='Q'&&opt!='C') opt=getchar();        if (opt=='C')        {            scanf("%d%d",&x,&y);            point_change(1,1,N,num[x],y);        }        else        {            scanf("%d%d",&u,&t);            ans=0;            int f1=top[u],f2=top[t];            while (f1!=f2)            {                if (h[f1]<h[f2])                {                    swap(u,t);                    swap(f1,f2);                }                ans^=query(1,1,N,num[f1],num[u]);                u=father[f1];                f1=top[u];            }            if (num[u]>num[t]) swap(u,t);            ans^=query(1,1,N,num[u],num[t]);            if (!ans) printf("No\n");            else printf("Yes\n");        }    }}

手写栈

#include<iostream>#include<cstring>#include<cstdio>using namespace std;const int max_n=5e5+5;const int max_m=max_n;const int max_e=max_m*2;const int max_tree=max_n*4;int n,m,x,y,u,t,ans,q,N,a[max_n];int tot,point[max_n],nxt[max_e],v[max_e];int size[max_n],h[max_n],father[max_n],son[max_n],top[max_n],num[max_n],val[max_n];int strack[max_n],cur[max_n],use[max_n];int tree[max_tree];inline void addedge(int x,int y){    ++tot; nxt[tot]=point[x]; point[x]=tot; v[tot]=y;    ++tot; nxt[tot]=point[y]; point[y]=tot; v[tot]=x;}inline void dfs_1(){    int temp=0; h[1]=1;    strack[++temp]=1; size[1]=1;    for (int i=1;i<=n;++i) cur[i]=point[i];    while (temp)    {        int x=strack[temp];        if (v[cur[x]]==father[x]) cur[x]=nxt[cur[x]];        if (!cur[x])        {            temp--;            if (father[x])            {                size[father[x]]+=size[x];                if (size[x]>size[son[father[x]]]) son[father[x]]=x;            }            continue;        }        int vt=v[cur[x]];        strack[++temp]=vt;        size[vt]=1; h[vt]=h[x]+1; father[vt]=x;        cur[x]=nxt[cur[x]];    }}inline void dfs_2(){    int temp=0;    strack[++temp]=1; top[1]=1; num[1]=++N; val[N]=a[1];    for (int i=1;i<=n;++i) cur[i]=point[i];    while (temp)    {        int x=strack[temp];        if (!use[x])        {            use[x]=1;            int vt=son[x];            if (vt)            {                strack[++temp]=vt;                top[vt]=top[x];                num[vt]=++N;                val[N]=a[vt];            }            continue;        }        while (cur[x]&&(v[cur[x]]==father[x]||v[cur[x]]==son[x])) cur[x]=nxt[cur[x]];        if (!cur[x])        {            temp--;            continue;        }        else        {            int vt=v[cur[x]];            strack[++temp]=vt;            top[vt]=vt; num[vt]=++N; val[N]=a[vt];            cur[x]=nxt[cur[x]];        }    }}inline void update(int now){    tree[now]=tree[now<<1]^tree[now<<1|1];}inline void build(int now,int l,int r){    int mid=(l+r)>>1;    if (l==r)    {        tree[now]=val[l];        return;    }    build(now<<1,l,mid);    build(now<<1|1,mid+1,r);    update(now);}inline void point_change(int now,int l,int r,int x,int v){    int mid=(l+r)>>1;    if (l==r)    {        tree[now]=v;        return;    }    if (x<=mid)        point_change(now<<1,l,mid,x,v);    else        point_change(now<<1|1,mid+1,r,x,v);    update(now);}inline int query(int now,int l,int r,int lrange,int rrange){    int mid=(l+r)>>1,ans=0;    if (lrange<=l&&r<=rrange)        return tree[now];    if (lrange<=mid)        ans^=query(now<<1,l,mid,lrange,rrange);    if (mid+1<=rrange)        ans^=query(now<<1|1,mid+1,r,lrange,rrange);    return ans;}int main(){    scanf("%d",&n);    for (int i=1;i<=n;++i) scanf("%d",&a[i]);    for (int i=1;i<n;++i)    {        scanf("%d%d",&x,&y);        addedge(x,y);    }    dfs_1();    dfs_2();    build(1,1,N);    scanf("%d",&q);    for (int i=1;i<=q;++i)    {        char opt=getchar();        while (opt!='Q'&&opt!='C') opt=getchar();        if (opt=='C')        {            scanf("%d%d",&x,&y);            point_change(1,1,N,num[x],y);        }        else        {            scanf("%d%d",&u,&t);            ans=0;            int f1=top[u],f2=top[t];            while (f1!=f2)            {                if (h[f1]<h[f2])                {                    swap(u,t);                    swap(f1,f2);                }                ans^=query(1,1,N,num[f1],num[u]);                u=father[f1];                f1=top[u];            }            if (num[u]>num[t]) swap(u,t);            ans^=query(1,1,N,num[u],num[t]);            if (!ans) printf("No\n");            else printf("Yes\n");        }    }}