poj 3237 Tree

    就是简单的树链剖分，但标记下传的时候一定要 ^1 而不能直接 = 1，我竟然WA在这么逗比的错误上不如一头撞死……

    上代码：

#include <cstdio>

#include <cstring>

#include <cstdlib>

#include <iostream>

#include <algorithm>

#define N 1100000

#define inf 0x7f7f7f7f

using namespace std;



struct sss

{

    int minnum, maxnum;

    int push;

}t[N*4];

int n, nowplace, bianp[N];

int p[N], next[N*2], v[N*2], c[N*2], bnum;

int fa[N], son[N], siz[N], deep[N], top[N], w[N];



void build_tree(int now, int l, int r)

{

    t[now].minnum = inf; t[now].maxnum = -inf; t[now].push = 0;

    if (l == r) return;

    int mid = (l+r)/2;

    build_tree(now*2, l, mid); build_tree(now*2+1, mid+1, r);

}



void downdate(int now)

{

    if (!t[now].push) return; t[now].push = 0;

    t[now*2].push ^= 1; t[now*2+1].push ^= 1;

    swap(t[now*2].maxnum, t[now*2].minnum);

    swap(t[now*2+1].maxnum, t[now*2+1].minnum);

    t[now*2].maxnum *= -1; t[now*2].minnum *= -1;

    t[now*2+1].maxnum *= -1; t[now*2+1].minnum *= -1;

}



void update(int now)

{

    t[now].maxnum = max(t[now*2].maxnum, t[now*2+1].maxnum);

    t[now].minnum = min(t[now*2].minnum, t[now*2+1].minnum);

}



void addbian(int x, int y)

{

    bnum++; next[bnum] = p[x]; p[x] = bnum; v[bnum] = y;

    bnum++; next[bnum] = p[y]; p[y] = bnum; v[bnum] = x;

}



void dfs_1(int now, int nowfa, int nowdeep)

{

    int k = p[now]; fa[now] = nowfa; deep[now] = nowdeep;

    int maxson = 0; son[now] = 0; siz[now] = 1;

    while (k)

    {

        if (v[k] != nowfa)

        {

            bianp[(k+1)/2] = v[k];

            dfs_1(v[k], now, nowdeep+1);

            siz[now] += siz[v[k]];

            if (siz[v[k]] > maxson)

            {

                maxson = siz[v[k]];

                son[now] = v[k];

            }

        }

        k = next[k];

    }

}



void dfs_2(int now, int nowfa, int nowtop)

{

    int k = p[now]; top[now] = nowtop; w[now] = ++nowplace;

    if (son[now]) dfs_2(son[now], now, nowtop);

    while (k)

    {

        if (v[k] != nowfa && v[k] != son[now])

            dfs_2(v[k], now, v[k]);

        k = next[k];

    }

}



int task(int now, int l, int r, int al, int ar)

{

    if (al <= l && r <= ar)    return t[now].maxnum;

    int mid = (l+r)/2, ans = -inf;

    downdate(now);

    if (al <= mid) ans = task(now*2, l, mid, al, ar);

    if (ar > mid) ans = max(ans, task(now*2+1, mid+1, r, al, ar));

    update(now); return ans;

}



void tneg(int now, int l, int r, int tl, int tr)

{

    if (tl <= l && r <= tr)

    {

        downdate(now);

        swap(t[now].maxnum, t[now].minnum);

        t[now].maxnum *= -1; t[now].minnum *= -1;

        t[now].push ^= 1; return;

    }

    int mid = (l+r)/2;

    downdate(now);

    if (tl <= mid) tneg(now*2, l, mid, tl, tr);

    if (tr > mid) tneg(now*2+1, mid+1, r, tl, tr);

    update(now); return;

}



void chan(int now, int l, int r, int cplace, int cnum)

{

    if (l == r)

    {

        t[now].maxnum = t[now].minnum = cnum;

        return;

    }

    int mid = (l+r)/2;

    downdate(now);

    if (cplace <= mid) chan(now*2, l, mid, cplace, cnum);

    else chan(now*2+1, mid+1, r, cplace, cnum);

    update(now); return;

}



void neg(int u, int v)

{

    int f1 = top[u], f2 = top[v];

    if (deep[f1] < deep[f2]) { swap(f1, f2); swap(u, v); }

    if (f1 == f2)

    {

        if (u == v) return;

        if (w[u] > w[v]) swap(u, v);

        tneg(1, 1, n, w[son[u]], w[v]);

        return;

    }

    tneg(1, 1, n, w[f1], w[u]); neg(fa[f1], v);

}



int find(int u, int v)

{

    int f1 = top[u],f2 = top[v];

    if (deep[f1] < deep[f2]) { swap(f1, f2); swap(u, v); }

    if (f1 == f2)

    {

        if (u == v) return -inf;

        if (w[u] > w[v]) swap(u, v);

        return task(1, 1, n, w[son[u]], w[v]);

    }

    int ans = task(1, 1, n, w[f1], w[u]);

    return max(ans, find(fa[f1], v));

}



int main()

{

    int T; scanf("%d", &T);

    while (T--)

    {

        scanf("%d", &n); memset(p, 0, sizeof(p));

        build_tree(1, 1, n); nowplace = 0; bnum = 0;

        for (int i = 1; i < n; ++i)

        {

            int x, y, z; scanf("%d%d%d", &x, &y, &z);

            addbian(x, y); c[i] = z;

        }

        dfs_1(1, 0, 1);

        dfs_2(1, 0, 1);

        for (int i = 1; i < n; ++i)

            chan(1, 1, n, w[bianp[i]], c[i]);

        char s[8];

        while (scanf("%s", s) != EOF)

        {

            if (s[0] == 'D') break;

            int x, y; scanf("%d%d", &x, &y);

            if (s[0] == 'Q') printf("%d\n", find(x, y));

            else if (s[0] == 'C') chan(1, 1, n, w[bianp[x]], y);

            else if (s[0]=='N') neg(x, y);

        }

    }

    return 0;

}