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*];
int n, nowplace, bianp[N];
int p[N], next[N*], v[N*], c[N*], 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 = ;
    if (l == r) return;
    int mid = (l+r)/;
    build_tree(now*, l, mid); build_tree(now*+, mid+, r);
}

void downdate(int now)
{
    if (!t[now].push) return; t[now].push = ;
    t[now*].push ^= ; t[now*+].push ^= ;
    swap(t[now*].maxnum, t[now*].minnum);
    swap(t[now*+].maxnum, t[now*+].minnum);
    t[now*].maxnum *= -; t[now*].minnum *= -;
    t[now*+].maxnum *= -; t[now*+].minnum *= -;
}

void update(int now)
{
    t[now].maxnum = max(t[now*].maxnum, t[now*+].maxnum);
    t[now].minnum = min(t[now*].minnum, t[now*+].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 = ; son[now] = ; siz[now] = ;
    while (k)
    {
        if (v[k] != nowfa)
        {
            bianp[(k+)/] = v[k];
            dfs_1(v[k], now, nowdeep+);
            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)/, ans = -inf;
    downdate(now);
    if (al <= mid) ans = task(now*, l, mid, al, ar);
    if (ar > mid) ans = max(ans, task(now*+, mid+, 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 *= -; t[now].minnum *= -;
        t[now].push ^= ; return;
    }
    int mid = (l+r)/;
    downdate(now);
    if (tl <= mid) tneg(now*, l, mid, tl, tr);
    if (tr > mid) tneg(now*+, mid+, 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)/;
    downdate(now);
    if (cplace <= mid) chan(now*, l, mid, cplace, cnum);
    else chan(now*+, mid+, 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(, , n, w[son[u]], w[v]);
        return;
    }
    tneg(, , 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(, , n, w[son[u]], w[v]);
    }
    int ans = task(, , 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, , sizeof(p));
        build_tree(, , n); nowplace = ; bnum = ;
        for (int i = ; i < n; ++i)
        {
            int x, y, z; scanf("%d%d%d", &x, &y, &z);
            addbian(x, y); c[i] = z;
        }
        dfs_1(, , );
        dfs_2(, , );
        for (int i = ; i < n; ++i)
            chan(, , n, w[bianp[i]], c[i]);
        char s[];
        while (scanf("%s", s) != EOF)
        {
            if (s[] == 'D') break;
            int x, y; scanf("%d%d", &x, &y);
            if (s[] == 'Q') printf("%d\n", find(x, y));
            else if (s[] == 'C') chan(, , n, w[bianp[x]], y);
            else if (s[]=='N') neg(x, y);
        }
    }
    return ;
}