HDU 3966 Aragorn's Story

HDU_3966

    树链剖分的题目，推荐一个讲树链剖分通俗易懂的博客：http://blog.sina.com.cn/s/blog_6974c8b20100zc61.html。

#include<stdio.h>
#include<string.h>
#define MAXD 50010
#define MAXM 100010
int N, M, Q, first[MAXD], e, next[MAXM], v[MAXM];
int fa[MAXD], dep[MAXD], size[MAXD], son[MAXD], top[MAXD], w[MAXD], cnt;
int a[MAXD], add[4 * MAXD], q[MAXD];
void Swap(int &x, int &y)
{
    int t;
    t = x, x = y, y = t;
}
void Add(int x, int y)
{
    v[e] = y;
    next[e] = first[x], first[x] = e ++;
}
void pushdown(int cur)
{
    if(add[cur])
    {
        add[cur << 1] += add[cur], add[cur << 1 | 1] += add[cur];
        add[cur] = 0;
    }
}
void prepare()
{
    int i, j, x, rear = 0;
    q[rear ++] = 1;
    fa[1] = 0, dep[1] = 1;
    for(i = 0; i < rear; i ++)
    {
        x = q[i];
        for(j = first[x]; j != -1; j = next[j])
            if(v[j] != fa[x])
            {
                fa[v[j]] = x, dep[v[j]] = dep[x] + 1;
                q[rear ++] = v[j];
            }
    }
    size[0] = 0;
    for(i = rear - 1; i >= 0; i --)
    {
        x = q[i];
        size[x] = 1, son[x] = 0;
        for(j = first[x]; j != -1; j = next[j])
            if(v[j] != fa[x])
            {
                size[x] += size[v[j]];
                if(size[v[j]] > size[son[x]])
                    son[x] = v[j];
            }
    }
    cnt = 0;
    memset(top, 0, sizeof(top));
    for(i = 0; i < rear; i ++)
    {
        x = q[i];
        if(top[x] == 0)
        {
            for(j = x; j != 0; j = son[j])
                top[j] = x, w[j] = ++ cnt;
        }
    }
}
void refresh(int cur, int x, int y, int s, int t, int v)
{
    int mid = (x + y) >> 1, ls = cur << 1, rs = cur << 1 | 1;
    if(x >= s && y <= t)
    {
        add[cur] += v;
        return ;
    }
    pushdown(cur);
    if(mid >= s)
        refresh(ls, x, mid, s, t, v);
    if(mid + 1 <= t)
        refresh(rs, mid + 1, y, s, t, v);
}
void init()
{
    int i, x, y;
    for(i = 1; i <= N; i ++)
        scanf("%d", &a[i]);
    e = 0;
    memset(first, -1, sizeof(first));
    for(i = 0; i < M; i ++)
    {
        scanf("%d%d", &x, &y);
        Add(x, y), Add(y, x);
    }
    prepare();
    memset(add, 0, sizeof(add));
    for(i = 1; i <= N; i ++)
        refresh(1, 1, N, w[i], w[i], a[i]);
}
int Search(int cur, int x, int y, int k)
{
    int mid = (x + y) >> 1, ls = cur << 1, rs = cur << 1 | 1;
    if(x == y)
        return add[cur];
    pushdown(cur);
    if(k <= mid)
        return Search(ls, x, mid, k);
    else
        return Search(rs, mid + 1, y, k);
}
void deal(int x, int y, int z)
{
    int fx = top[x], fy = top[y];
    while(fx != fy)
    {
        if(dep[fx] > dep[fy])
            Swap(fx, fy), Swap(x, y);
        refresh(1, 1, N, w[fy], w[y], z);
        y = fa[fy], fy = top[y];
    }
    if(dep[x] > dep[y])
        Swap(x, y);
    refresh(1, 1, N, w[x], w[y], z);
}
void solve()
{
    int i, x, y, z;
    char op[5];
    for(i = 0; i < Q; i ++)
    {
        scanf("%s%d", op, &x);
        if(op[0] == 'Q')
            printf("%d\n", Search(1, 1, N, w[x]));
        else
        {
            scanf("%d%d", &y, &z);
            if(op[0] == 'I')
                deal(x, y, z);
            else
                deal(x, y, -z);
        }
    }
}
int main()
{
    while(scanf("%d%d%d", &N, &M, &Q) == 3)
    {
        init();
        solve();
    }
    return 0;
}