洛谷 - P2146 - 软件包管理器 - 重链剖分

https://www.luogu.org/problem/P2146

继续重链剖分。
这里好像很好懂，每次安装软件就区间改值赋值整个路径是1，然后比较前后的sum值变化就可以了。事实上后一次的sum值必定是dep。卸载的话，依赖它的都没了，相当于清空整棵子树。

#include<bits/stdc++.h>
#define lc (o<<1)
#define rc (o<<1|1)
typedef long long ll;
using namespace std;

const int MAXN = 100000 + 5;
int dep[MAXN], siz[MAXN],  son[MAXN], fa[MAXN], top[MAXN], tid[MAXN], rnk[MAXN], cnt;

int n, m, r;
int head[MAXN], etop;

struct Edge {
    int v, next;
} e[MAXN * 2];

inline void init(int n) {
    etop = 0;
    memset(head, -1, sizeof(head[0]) * (n + 1));
}

inline void addedge(int u, int v) {
    e[++etop].v = v;
    e[etop].next = head[u];
    head[u] = etop;
    e[++etop].v = u;
    e[etop].next = head[v];
    head[v] = etop;
}

struct SegmentTree {
    int sum[MAXN * 4];
    int lz[MAXN * 4];//lz=1,set to 1;lz=-1,set to 0;

    void pushup(int o) {
        sum[o] = sum[lc] + sum[rc];
    }

    void pushdown(int o, int l, int r) {
        if(lz[o]) {
            lz[lc] = lz[o];
            lz[rc] = lz[o];
            int m = l + r >> 1;
            if(lz[o] == 1) {
                sum[lc] = (m - l + 1);
                sum[rc] = (r - m) ;
            } else {
                sum[lc] = 0;
                sum[rc] = 0;
            }
            lz[o] = 0;
        }
    }

    void update(int o, int l, int r, int ql, int qr, int v) {
        if(ql <= l && r <= qr) {
            lz[o] = v;
            if(v == 1)
                sum[o] = r - l + 1;
            else
                sum[o] = 0;
        } else {
            pushdown(o, l, r);
            int m = (l + r) >> 1;
            if(ql <= m)
                update(lc, l, m, ql, qr, v);
            if(qr >= m + 1)
                update(rc, m + 1, r, ql, qr, v);
            pushup(o);
        }
    }

    int query(int o, int l, int r, int ql, int qr) {
        if(ql <= l && r <= qr) {
            return sum[o];
        } else {
            pushdown(o, l, r);
            int m = (l + r) >> 1;
            int res = 0;
            if(ql <= m)
                res += query(lc, l, m, ql, qr);
            if(qr >= m + 1)
                res += query(rc, m + 1, r, ql, qr);
            return res;
        }
    }
} st;

void init1() {
    dep[r] = 1;
}

void dfs1(int u, int t) {
    siz[u] = 1, son[u] = -1, fa[u] = t;
    for(int i = head[u]; i != -1; i = e[i].next) {
        int v = e[i].v;
        if(v == t)
            continue;
        dep[v] = dep[u] + 1;
        dfs1(v, u);
        siz[u] += siz[v];
        if(son[u] == -1 || siz[v] > siz[son[u]])
            son[u] = v;
    }
}

void init2() {
    cnt = 0;
}

void dfs2(int u, int t) {
    top[u] = t;
    tid[u] = ++cnt;
    rnk[cnt] = u;
    if(son[u] == -1)
        return;
    dfs2(son[u], t);
    for(int i = head[u]; i != -1; i = e[i].next) {
        int v = e[i].v;
        if(v == fa[u] || v == son[u])
            continue;
        dfs2(v, v);
    }
}

int query1(int u, int v) {
    int ret = 0;
    for(int tu = top[u], tv = top[v]; tu != tv; u = fa[tu], tu = top[u]) {
        if(dep[tu] < dep[tv])
            swap(u, v), swap(tu, tv);
        ret += st.query(1, 1, n, tid[tu], tid[u]);
    }
    if(dep[u] > dep[v])
        swap(u, v);
    ret += st.query(1, 1, n, tid[u], tid[v]);
    return ret;
}

int query2(int u) {
    return st.query(1, 1, n, tid[u], tid[u]+siz[u]-1);
}

void update1(int u, int v, int val) {
    for(int tu = top[u], tv = top[v]; tu != tv; u = fa[tu], tu = top[u]) {
        if(dep[tu] < dep[tv])
            swap(u, v), swap(tu, tv);
        st.update(1, 1, n, tid[tu], tid[u], val);
    }
    if(dep[u] > dep[v])
        swap(u, v);
    st.update(1, 1, n, tid[u], tid[v], val);
    return;
}

void update2(int u, int val) {
    return st.update(1, 1, n, tid[u], tid[u]+siz[u]-1,val);
}

void install() {
    int x;
    scanf("%d", &x);
    int sum1 = query1(0, x);
    update1(0, x, 1);
    int sum2 = query1(0,x);
    printf("%d\n", sum2 - sum1);
    return ;
}

void uninstall() {
    int x;
    scanf("%d", &x);
    int sum1 = query2(x);
    update2(x, -1);
    printf("%d\n", sum1);
    return;
}

int main() {
#ifdef Yinku
    freopen("Yinku.in", "r", stdin);
#endif // Yinku
    scanf("%d", &n);
    init(n);
    for(int i = 1, u; i <= n - 1; ++i) {
        scanf("%d", &u);
        addedge(i, u);
    }
    r = 0;
    init1();
    dfs1(r, -1);
    init2();
    dfs2(r, r);
    char s[50];
    scanf("%d", &m);
    for(int i = 1; i <= m; ++i) {
        scanf("%s", s);
        switch(s[0]) {
            case 'i':
                install();
                break;
            case 'u':
                uninstall();
                break;
        }
    }
    return 0;
}