bzoj4196 [Noi2015]软件包管理器

Posted 2020-09-22 逢山开路 遇水架桥

传送门：http://www.lydsy.com/JudgeOnline/problem.php?id=4196

【题解】

百年不用算法：树链剖分

刚刚推了一发还是很简单的嘛

在支持子树修改的同时支持链修改。

由于子树肯定是在线段树中连在一坨的所以一样修改。

# include <stdio.h>
# include <string.h>
# include <iostream>
# include <algorithm>
// # include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
const int M = 5e5 + 10;
const int mod = 1e9+7;

# define RG register
# define ST static

int n, Q, a[M], par[M];
int head[M], nxt[M], to[M], tot=0;
inline void add(int u, int v) {
    ++tot; nxt[tot] = head[u]; head[u] = tot; to[tot] = v;
}

int sz[M], mx[M];
inline void dfs1(int x) {
    int u = 0; sz[x] = 1;
    for (int i=head[x]; i; i=nxt[i]) {
        dfs1(to[i]);
        sz[x] += sz[to[i]];
        if(sz[to[i]] > u) {
            u = sz[to[i]];
            mx[x] = to[i];
        }
    }
}

int top[M], pos[M], DFN, beg[M], end[M];
inline void dfs2(int x, int tp) {
    beg[x] = pos[x] = ++DFN; top[x] = tp;
    if(mx[x]) dfs2(mx[x], tp);
    for (int i=head[x]; i; i=nxt[i]) 
        if(to[i] != mx[x]) dfs2(to[i], to[i]);
    end[x] = DFN;    
}

struct SMT {
    int w[M];
    int tag[M];
    # define ls (x<<1)
    # define rs (x<<1|1)
    inline void up(int x) {
        if(!x) return ;
        w[x] = w[ls] + w[rs];
    }
    inline void pushtag(int x, int l, int r, int d) {
        if(!x) return ;
        w[x] = d*(r-l+1);
        tag[x] = d;
    }
    inline void down(int x, int l, int r) {
        if(!x) return ;
        if(tag[x] == -1) return ;
        int mid = l+r>>1;
        pushtag(ls, l, mid, tag[x]);
        pushtag(rs, mid+1, r, tag[x]);
        tag[x] = -1;
    }
    inline void edt(int x, int l, int r, int L, int R, int d) {
        if(L <= l && r <= R) {
            pushtag(x, l, r, d);
            return ;
        }
        down(x, l, r);
        int mid = l+r>>1;
        if(L <= mid) edt(ls, l, mid, L, R, d);
        if(R > mid) edt(rs, mid+1, r, L, R, d);    
        up(x);
    }
    inline int query(int x, int l, int r, int L, int R, int d) {
        if(L <= l && r <= R) {
            if(d == 1) return w[x];
            else return r-l+1-w[x];
        }
        down(x, l, r);
        int mid = l+r>>1, ret = 0;
        if(L <= mid) ret += query(ls, l, mid, L, R, d);
        if(R > mid) ret += query(rs, mid+1, r, L, R, d);
        return ret;
    }
}T;



int main() {
    cin >> n;
    for (int i=2; i<=n; ++i) {
        scanf("%d", par+i); ++par[i];
        add(par[i], i);
    }
    dfs1(1);
    dfs2(1, 1);
//    for (int i=1; i<=n; ++i) printf("x = %d, top = %d, pos = %d\n", i, top[i], pos[i]);
    for (int i=1; i<=n*4; ++i) T.w[i] = 0, T.tag[i] = -1;
    cin >> Q;
    char str[23]; int x;
    while(Q--) {
        scanf("%s%d", str, &x); ++x;
        if(str[0] == ‘i‘) {
            // install
            int t = x, tp, ans = 0;
            while(1) {
                tp = top[t];
                ans += T.query(1, 1, n, pos[tp], pos[t], 0);
                if(tp == 1) break;
                t = par[tp];
            }
            printf("%d\n", ans);
            t = x;
            while(1) {
                tp = top[t];
                T.edt(1, 1, n, pos[tp], pos[t], 1);
                if(tp == 1) break;
                t = par[tp];
            }
        } else {
            // uninstall
//            printf("%d %d\n", beg[x], end[x]);
            printf("%d\n", T.query(1, 1, n, beg[x], end[x], 1));
            T.edt(1, 1, n, beg[x], end[x], 0);
        }
    }
    return 0;
}

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