POJ 3237 Tree （树链剖分 路径更新）

比裸的树链剖分多个区间更新

/* ***********************************************Author        :kuangbinCreated Time  :2013/8/17 4:04:42File Name     :F:\2013ACM练习\专题学习\数链剖分\POJ3237Tree.cpp************************************************ */#include <stdio.h>#include <string.h>#include <iostream>#include <algorithm>#include <vector>#include <queue>#include <set>#include <map>#include <string>#include <math.h>#include <stdlib.h>#include <time.h>using namespace std;const int MAXN = 100010;struct Edge{    int to,next;}edge[MAXN*2];int head[MAXN],tot;int top[MAXN];//top[v]表示v所在的重链的顶端节点int fa[MAXN]; //父亲节点int deep[MAXN];//深度int num[MAXN];//num[v]表示以v为根的子树的节点数int p[MAXN];//p[v]表示v与其父亲节点的连边在线段树中的位置int fp[MAXN];//和p数组相反int son[MAXN];//重儿子int pos;void init(){    tot = 0;    memset(head,-1,sizeof(head));    pos = 0;    memset(son,-1,sizeof(son));}void addedge(int u,int v){    edge[tot].to = v;edge[tot].next = head[u];head[u] = tot++;}void dfs1(int u,int pre,int d) //第一遍dfs求出fa,deep,num,son{    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;        }    }}void getpos(int u,int sp) //第二遍dfs求出top和p{    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);    }}//线段树struct Node{    int l,r;    int Max;    int Min;    int ne;}segTree[MAXN*3];void build(int i,int l,int r){    segTree[i].l = l;    segTree[i].r = r;    segTree[i].Max = 0;    segTree[i].Min = 0;    segTree[i].ne = 0;    if(l == r)return;    int mid = (l+r)/2;    build(i<<1,l,mid);    build((i<<1)|1,mid+1,r);}void push_up(int i){    segTree[i].Max = max(segTree[i<<1].Max,segTree[(i<<1)|1].Max);    segTree[i].Min = min(segTree[i<<1].Min,segTree[(i<<1)|1].Min);}void push_down(int i){    if(segTree[i].l == segTree[i].r)return;    if(segTree[i].ne)    {        segTree[i<<1].Max = -segTree[i<<1].Max;        segTree[i<<1].Min = -segTree[i<<1].Min;        swap(segTree[i<<1].Min,segTree[i<<1].Max);        segTree[(i<<1)|1].Max = -segTree[(i<<1)|1].Max;        segTree[(i<<1)|1].Min = -segTree[(i<<1)|1].Min;        swap(segTree[(i<<1)|1].Max,segTree[(i<<1)|1].Min);        segTree[i<<1].ne ^= 1;        segTree[(i<<1)|1].ne ^= 1;        segTree[i].ne = 0;    }}void update(int i,int k,int val) // 更新线段树的第k个值为val{    if(segTree[i].l == k && segTree[i].r == k)    {        segTree[i].Max = val;        segTree[i].Min = val;        segTree[i].ne = 0;        return;    }    push_down(i);    int mid = (segTree[i].l + segTree[i].r)/2;    if(k <= mid)update(i<<1,k,val);    else update((i<<1)|1,k,val);    push_up(i);}void ne_update(int i,int l,int r) // 更新线段树的区间[l,r]取反{    if(segTree[i].l == l && segTree[i].r == r)    {        segTree[i].Max = -segTree[i].Max;        segTree[i].Min = -segTree[i].Min;        swap(segTree[i].Max,segTree[i].Min);        segTree[i].ne ^= 1;        return;    }    push_down(i);    int mid = (segTree[i].l + segTree[i].r)/2;    if(r <= mid)ne_update(i<<1,l,r);    else if(l > mid) ne_update((i<<1)|1,l,r);    else    {        ne_update(i<<1,l,mid);        ne_update((i<<1)|1,mid+1,r);    }    push_up(i);}int query(int i,int l,int r)  //查询线段树中[l,r] 的最大值{    if(segTree[i].l == l && segTree[i].r == r)        return segTree[i].Max;    push_down(i);    int mid = (segTree[i].l + segTree[i].r)/2;    if(r <= mid)return query(i<<1,l,r);    else if(l > mid)return query((i<<1)|1,l,r);    else return max(query(i<<1,l,mid),query((i<<1)|1,mid+1,r));    push_up(i);}int findmax(int u,int v)//查询u->v边的最大值{    int f1 = top[u], f2 = top[v];    int tmp = -100000000;    while(f1 != f2)    {        if(deep[f1] < deep[f2])        {            swap(f1,f2);            swap(u,v);        }        tmp = max(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 max(tmp,query(1,p[son[u]],p[v]));}void Negate(int u,int v)//把u-v路径上的边的值都设置为val{    int f1 = top[u], f2 = top[v];    while(f1 != f2)    {        if(deep[f1] < deep[f2])        {            swap(f1,f2);            swap(u,v);        }        ne_update(1,p[f1],p[u]);        u = fa[f1]; f1 = top[u];    }    if(u == v)return;    if(deep[u] > deep[v]) swap(u,v);    return ne_update(1,p[son[u]],p[v]);}int e[MAXN][3];int main(){    //freopen("in.txt","r",stdin);    //freopen("out.txt","w",stdout);    int T;    int n;    scanf("%d",&T);    while(T--)    {        init();        scanf("%d",&n);        for(int i = 0;i < n-1;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(1,0,pos-1);        for(int i = 0;i < n-1; 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];        int u,v;        while(scanf("%s",op) == 1)        {            if(op[0] == 'D')break;            scanf("%d%d",&u,&v);            if(op[0] == 'Q')                printf("%d\n",findmax(u,v));//查询u->v路径上边权的最大值            else if(op[0] == 'C')                update(1,p[e[u-1][1]],v);//改变第u条边的值为v            else Negate(u,v);        }    }    return 0;}