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  • hdu6110

    #include <cstdio>
    #include <iostream>
    #include <cmath>
    #include <cstring>
    #include <algorithm>
    #include <vector>
    #include <queue>
    #define fi first
    #define se second
    using namespace std;
    typedef long long LL;
    typedef pair<int,int> pii;
    
    struct fastio{
        char s[100005];
        int it,len;
        fastio(){it=len=0;}
        inline char get(){
            if(it<len)return s[it++];it=0;
            len=fread(s,1,100000,stdin);
            if(len==0)return EOF;else return s[it++];
        }
        bool notend(){
            char c=get();
            while(c==' '||c=='
    ')c=get();
            if(it>0)it--;
            return c!=EOF;
        }
    }BUFF;
    #define read(x) x=getnum()
    #define write(x) putnum(x),putchar(' ')
    #define writeln(x) putnum(x),putchar('
    ')
    
    inline LL getnum(){
        LL r=0;bool ng=0;char c;c=BUFF.get();
        while(c!='-'&&(c<'0'||c>'9'))c=BUFF.get();
        if(c=='-')ng=1,c=BUFF.get();
        while(c>='0'&&c<='9')r=r*10+c-'0',c=BUFF.get();
        return ng?-r:r;
    }
    template<class T> inline void putnum(T x){
        if(x<0)putchar('-'),x=-x;
        register short a[20]={},sz=0;
        while(x)a[sz++]=x%10,x/=10;
        if(sz==0)putchar('0');
        for(int i=sz-1;i>=0;i--)putchar('0'+a[i]);
    }
    inline char getreal(){char c=BUFF.get();while(c<=32)c=BUFF.get();return c;}
    
    
    const int MXN = 5e5 + 5;
    const int mod = 1e9 + 7;
    const int INF = 0x3f3f3f3f;
    
    int n, m, s;
    int head[MXN], tot;
    int up[MXN][21], dep[MXN], sum[MXN];
    struct lp{
        int v, nex, w;
    }cw[MXN*3];
    void add_1(int a,int b,int c){
        cw[++tot].v=b;cw[tot].nex=head[a];cw[tot].w=c;
        head[a]=tot;
        cw[++tot].v=a;cw[tot].nex=head[b];cw[tot].w=c;
        head[b]=tot;
    }
    void search(int u,int ba,int d) {
        dep[u] = d;
        up[u][0] = ba;
        for(int i = 1; i < 20; ++i) {
            up[u][i] = up[up[u][i-1]][i-1];
        }
        for(int i = head[u]; ~i; i = cw[i].nex) {
            int v = cw[i].v;
            if(v == ba) continue;
            up[v][0] = u;
            sum[v] = sum[u] + cw[i].w;
            search(v, u, d + 1);
        }
    }
    int LCA(int x,int y) {
        if(dep[x] < dep[y]) swap(x, y);
        int k = dep[x] - dep[y];
        for(int i = 0; i < 20; ++i) {
            if((1<<i)&k) {
                x = up[x][i];
            }
        }
        if(x == y) return x;
        for(int i = 19; i >= 0; --i) {
            if(up[x][i] != up[y][i]) {
                x = up[x][i];
                y = up[y][i];
            }
        }
        return up[x][0];
    }
    pair<int,int> tree[MXN<<2];
    bool cmp(int a,int b) {
        return dep[a] > dep[b];
    }
    pii UN(pii x, pii y) {
        int a[4];
        a[0] = LCA(x.fi,y.fi), a[1] = LCA(x.fi,y.se);
        a[2] = LCA(x.se,y.fi), a[3] = LCA(x.se,y.se);
        sort(a, a + 4, cmp);
        return pii(a[0], a[1]);
    }
    void build(int l,int r,int rt) {
        if(l == r) {
            scanf("%d%d",&tree[rt].fi,&tree[rt].se);
            return;
        }
        int mid=(l+r)>>1;
        build(l,mid,rt<<1);build(mid+1,r,rt<<1|1);
        tree[rt] = UN(tree[rt<<1], tree[rt<<1|1]);
    }
    pii query(int L,int R,int l,int r,int rt) {
        if(L <= l && r <= R) {
            return tree[rt];
        }
        int mid = (l + r) >> 1;
        if(L > mid) return query(L, R, mid+1, r, rt<<1|1);
        else if(R <= mid) return query(L,R,l,mid,rt<<1);
        return UN(query(L,mid,l,mid,rt<<1),query(mid+1,R,mid+1,r,rt<<1|1));
    }
    int main(){
        while(~scanf("%d", &n)) {
            for(int i = 1; i <= n; ++i) {
                sum[i] = 0;dep[i] = 0;
                for(int j = 0; j < 20; ++j) up[i][j] = 0;
                head[i] = -1;
            }
            tot = -1;
            for(int i = 1, a, b, c; i < n; ++i) {
                scanf("%d%d%d", &a, &b, &c);
                add_1(a, b,c);
            }
            search(1, 1, 1);
            scanf("%d", &m);
            build(1,m,1);
            scanf("%d", &s);
            for(int tim = 0, l, r; tim < s; ++ tim) {
                scanf("%d%d", &l, &r);
                pii ans = query(l,r,1,m,1);
                printf("%d
    ", sum[ans.fi]+sum[ans.se]-2*sum[LCA(ans.fi,ans.se)]);
            }
        }
        return 0;
    }
    
    
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  • 原文地址:https://www.cnblogs.com/Cwolf9/p/9904290.html
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