FZU - 2082 过路费

树剖的裸题，中文题面所以就不多解释了，当然操作二，就是简单的求过路费之和，因为路径唯一，他的那个最少过路费我也是醉了。

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
typedef long long LL;
const int INF = 0x3f3f3f3f;
const int maxn = 50000+10;
inline int read(){int x=0,f=1;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}return x*f;
}
struct Point{int x,y,val;
}point[maxn];
int head[maxn],edge_cnt,tot,value[maxn];
struct Edge{int to,next;
}edge[maxn<<1];
inline void ADD(int u,int v){edge[edge_cnt].to = v;edge[edge_cnt].next = head[u];head[u] = edge_cnt++;
}
int N,M;
int size[maxn],son[maxn],deep[maxn],fa[maxn];
void dfs1(int now,int father,int Deep){fa[now] = father;size[now] = 1;deep[now] = Deep;son[now] = 0;for(int i = head[now]; ~i; i = edge[i].next){int v = edge[i].to;if(v != father){dfs1(v,now,Deep+1);size[now] += size[v];if(size[son[now]] < size[v])son[now] = v;}}
}
int ID[maxn],Rank[maxn],top[maxn];
void dfs2(int now,int Top){top[now] = Top;ID[now] = ++tot;Rank[ID[now]] = now;if(son[now])dfs2(son[now],Top);for(int i = head[now]; ~i; i = edge[i].next){int v = edge[i].to;if(v != fa[now] && v != son[now]){dfs2(v,v);}}
}
struct Info{int l,r,sum;
};
#define MID int Mid = (tree[now].l+tree[now].r)>>1
struct SGT{Info tree[maxn<<2];inline void pushUp(int now){tree[now].sum = tree[now<<1].sum+tree[now<<1|1].sum;}void build(int now,int l,int r){tree[now].l = l;tree[now].r = r;if(l == r){tree[now].sum = value[Rank[l]];return;}int Mid = (l+r)>>1;build(now<<1,l,Mid);build(now<<1|1,Mid+1,r);pushUp(now);}inline void update(int now,int idx,int val){if(tree[now].l == tree[now].r){tree[now].sum = val;return;}MID;if(idx <= Mid)update(now<<1,idx,val);elseupdate(now<<1|1,idx,val);pushUp(now);}inline int query(int now,int l,int r){if(l <= tree[now].l && tree[now].r <= r)return tree[now].sum;MID;int ans = 0;if(l <= Mid)ans += query(now<<1,l,r);if(Mid < r)ans += query(now<<1|1,l,r);return ans;}
};
SGT sgt;
int work(int u,int v){int ans = 0;int tpu = top[u];int tpv = top[v];while(tpu != tpv){if(deep[tpu] < deep[tpv]){swap(u,v);swap(tpu,tpv);}ans += sgt.query(1,ID[tpu],ID[u]);u = fa[tpu];tpu = top[u];}if(u == v)return ans;if(deep[u] > deep[v])swap(u,v);ans += sgt.query(1,ID[son[u]],ID[v]);return ans;
}
int main(){while(~scanf("%d %d",&N,&M)){memset(head,-1,sizeof(head));edge_cnt = tot = 0;for(int i = 1; i < N; i++){point[i].x = read();point[i].y = read();point[i].val = read();ADD(point[i].x,point[i].y);ADD(point[i].y,point[i].x);}dfs1(1,0,0);dfs2(1,1);value[1] = 0;for(int i = 1; i < N; i++){if(deep[point[i].x] < deep[point[i].y])swap(point[i].x,point[i].y);value[point[i].x] = point[i].val;}sgt.build(1,1,N);int op,u,v;while(M--){op = read();u = read();v = read();if(!op)sgt.update(1,ID[point[u].x],v);elseprintf("%d\n",work(u,v));}}return 0;
}

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