poj-3237(树链剖分)

来源：互联网发布：数控车床g71车圆球编程编辑：程序博客网时间：2024/05/21 11:14
对树有三种操作：
Q~ a b 询问a~b路径的最大值；
N~ a b 对a~b路径上的数进行取反操作；（a=-a）
C~ a b 将第a条边的值改为b；
对于取反操作，记录区间的最大和最小值和标记k，更新线段即可。
//#pragma comment(linker, "/STACK:1024000000,1024000000")#include<iostream>#include<stdio.h>#include<math.h>#include <string>#include<string.h>#include<map>#include<queue>#include<set>#include<utility>#include<vector>#include<algorithm>#include<stdlib.h>using namespace std;#define eps 1e-8#define pii pair<int,int>#define inf 0x3f3f3f3f#define rd(x) scanf("%d",&x)#define rd2(x,y) scanf("%d%d",&x,&y)#define ll long long int#define mod 1000000007#define maxn 100005#define maxm 1000005struct edge{    int to,next;}edge[maxn*2];int head[maxn],tot;int top[maxn];//v所在重链的顶端节点int fa[maxn];int deep[maxn];int num[maxn];//表示以v为根的子树的节点数int p[maxn];//表示v与其父亲节点的连边在线段树中的位置int fp[maxn];//该边的儿子int son[maxn];//重儿子int pos;int maxx(int a,int b){return a>b?a:b;}int mixx(int a,int b){return a<b?a:b;}void init(){    tot=0;pos=0;    memset(head,-1,sizeof(head));    memset(son,-1,sizeof(son));}void addedge(int u,int v){    edge[tot].to=v;edge[tot].next=head[u];head[u]=tot++;}//第一遍dfs求fa,deep,num,sonvoid dfs1(int u,int pre,int d){    deep[u]=d;    fa[u]=pre;    num[u]=1;    for(int i=head[u];i!=-1;i=edge[i].next){        int v=edge[i].to;        if(v!=pre){            dfs1(v,u,d+1);            num[u]+=num[v];            if(son[u]==-1||num[v]>num[son[u]]) son[u]=v;        }    }}//第二遍dfs求出top和pvoid getpos(int u,int sp){    top[u]=sp;    p[u]=pos++;    fp[p[u]]=u;    if(son[u]==-1) return;    getpos(son[u],sp);    for(int i=head[u];i!=-1;i=edge[i].next){        int v=edge[i].to;        if(v!=son[u]&&v!=fa[u]) getpos(v,v);    }}struct node{    int l,r,ma,mi,k;//k=1表示其左右儿子区间需要取反}tree[maxn*3];void build(int i,int l,int r){    tree[i].l=l;tree[i].r=r;    tree[i].k=0;   // tree[i].ma=-inf;   // tree[i].mi=inf;    if(l==r) return;    int mid=(l+r)>>1;    build(i<<1,l,mid);    build((i<<1)|1,mid+1,r);}void push_down(int i){//向下更新取反    if(tree[i].l==tree[i].r) return;    if(tree[i].k){        tree[i].k^=1;        tree[i<<1].k^=1;tree[(i<<1)|1].k^=1;        tree[i<<1].mi=-tree[i<<1].mi;tree[i<<1].ma=-tree[i<<1].ma;        tree[(i<<1)|1].mi=-tree[(i<<1)|1].mi;tree[(i<<1)|1].ma=-tree[(i<<1)|1].ma;        swap(tree[i<<1].ma,tree[i<<1].mi);        swap(tree[(i<<1)|1].ma,tree[(i<<1)|1].mi);    }}void push_up(int i){    tree[i].ma=maxx(tree[i<<1].ma,tree[(i<<1)|1].ma);    tree[i].mi=mixx(tree[i<<1].mi,tree[(i<<1)|1].mi);}int query(int i,int l,int r){    if(tree[i].l==l&&tree[i].r==r) return tree[i].ma;    push_down(i);    int mid=(tree[i].l+tree[i].r)>>1;    if(r<=mid) return query(i<<1,l,r);    else if(l>mid) return query((i<<1)|1,l,r);    else return maxx(query(i<<1,l,mid),query((i<<1)|1,mid+1,r));}void change(int i,int l,int r){    if(tree[i].l==l&&tree[i].r==r){        tree[i].k^=1;        tree[i].ma=-tree[i].ma;tree[i].mi=-tree[i].mi;        swap(tree[i].ma,tree[i].mi);        return;    }    push_down(i);    int mid=(tree[i].l+tree[i].r)>>1;    if(r<=mid) change(i<<1,l,r);    else if(l>mid) change((i<<1)|1,l,r);    else{        change(i<<1,l,mid);        change((i<<1)|1,mid+1,r);    }    push_up(i);}void update(int i,int k,int val){    if(tree[i].l==tree[i].r) {        tree[i].ma=tree[i].mi=val;        return;    }    push_down(i);    int mid=(tree[i].l+tree[i].r)>>1;    if(k<=mid) update(i<<1,k,val);    else update((i<<1)|1,k,val);    push_up(i);}int findma(int u,int v){//最大值    int f1=top[u],f2=top[v];    int tmp=-1000000000;    while(f1!=f2){        if(deep[f1]<deep[f2]){            swap(f1,f2);            swap(u,v);        }        tmp=maxx(tmp,query(1,p[f1],p[u]));        u=fa[f1];f1=top[u];    }    if(u==v) return tmp;    if(deep[u]>deep[v]) swap(u,v);    return maxx(tmp,query(1,p[son[u]],p[v]));}void change(int u,int v){//取反    int f1=top[u],f2=top[v];   // int tmp=-1000000000;    while(f1!=f2){        if(deep[f1]<deep[f2]){            swap(f1,f2);            swap(u,v);        }        //tmp=maxx(tmp,query(1,p[f1],p[u]));        change(1,p[f1],p[u]);        u=fa[f1];f1=top[u];    }    if(u==v) return ;    if(deep[u]>deep[v]) swap(u,v);    //return maxx(tmp,query(1,p[son[u]],p[v]));    change(1,p[son[u]],p[v]);}int t,n,a,b,c;int e[maxn][3];int main(){    rd(t);    while(t--){        rd(n);        init();        for(int i=1;i<n;i++){            scanf("%d%d%d",&e[i][0],&e[i][1],&e[i][2]);            addedge(e[i][0],e[i][1]);            addedge(e[i][1],e[i][0]);        }        dfs1(1,0,0);        getpos(1,1);        build(1,1,n-1);        for(int i=1;i<n;i++){            if(deep[e[i][0]]>deep[e[i][1]]) swap(e[i][0],e[i][1]);            update(1,p[e[i][1]],e[i][2]);        }        char op[10];        while(scanf("%s",op)){            if(op[0]=='D') break;            scanf("%d%d",&a,&b);            if(op[0]=='Q') printf("%d\n",findma(a,b));            else if(op[0]=='N') change(a,b);            else update(1,p[e[a][1]],b);        }    }    return 0;}
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