宠物收养所

题目描述

思路

代码

#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <cmath>

const int MAX = 8e4 + 5, mod = 1e6;
int n, m, inf = 0x3f3f3f3f;
int ans, rt, tot;
bool flag;
struct Node {
    int lc, rc, key, pri, cnt, size;
    #define lc(x) t[x].lc
    #define rc(x) t[x].rc
    #define key(x) t[x].key
    #define pri(x) t[x].pri
    #define cnt(x) t[x].cnt
    #define size(x) t[x].size
} t[MAX];

inline int read() {
    int s = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') {
        if (ch == '-') f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') s = s * 10 + ch - '0', ch = getchar();
    return s * f;
}
void write(int x) {
    if (x > 9) write(x / 10);
    putchar(x % 10 + '0');
}
void update(int r) { size(r) = size(lc(r)) + size(rc(r)) + cnt(r); }
void zig(int &r) {
    int s = lc(r);
    lc(r) = rc(s);
    rc(s) = r;
    size(s) = size(r);
    update(r);
    r = s;
}
void zag(int &r) {
    int s = rc(r);
    rc(r) = lc(s);
    lc(s) = r;
    size(s) = size(r);
    update(r);
    r = s;
}
void insert(int &r, int k) {
    if (!r) {
        r = ++tot, key(r) = k, pri(r) = rand();
        cnt(r) = size(r) = 1, lc(r) = rc(r) = 0;
        return;
    } else ++size(r);
    if (k == key(r)) ++cnt(r);
    else if (k < key(r)) {
        insert(lc(r), k);
        if (pri(lc(r)) < pri(r)) zig(r);
    } else {
        insert(rc(r), k);
        if (pri(rc(r)) < pri(r)) zag(r);
    }
}

void del(int &r, int k) {
    if (key(r) == k) {
        if (cnt(r) >= 2) --cnt(r), --size(r);
        else if(!lc(r) || !rc(r)) r = lc(r) + rc(r);
        else if(pri(lc(r)) < pri(rc(r))) zig(r), del(r, k);
        else zag(r), del(r, k);
        return;
    } 
    --size(r);
    if (k < key(r)) del(lc(r), k);
    else del(rc(r), k);
}

int queryPre(int k) {
    int r = rt, res = inf;
    while (r) {
        if (key(r) <= k) res = key(r), r = rc(r);
        else r = lc(r);
    }
    return res;
}
int queryNxt(int k) {
    int r = rt, res = inf;
    while (r) {
        if (k < key(r)) res = key(r), r = lc(r);
        else r = rc(r);
    }
    return res;
}

int queryKth(int k) {
    int r = rt, res = inf;
    while (r) {
        if (size(lc(r)) < k && size(lc(r)) + cnt(r) >= k) return key(r);
        else if(size(lc(r)) >= k) r = lc(r); 
        else k -= size(lc(r)) + cnt(r), r = rc(r);
    }
    return res;
}

int queryRand(int k) {
    int r = rt, res = 0;
    while (r) {
        if (k == key(r)) return size(lc(r)) + cnt(r) + 1;
        else if (k < key(r)) r = lc(r); 
        else res += size(lc(r)) + cnt(r), r = rc(r);   
    }
    return res;
}
void show(int x) {
    printf("%d %d %d %d\n", lc(x), rc(x), key(x), pri(x));
    if (lc(x) != 0) show(lc(x));
    if (rc(x) != 0) show(rc(x));
}
int main() {
    n = read();
    srand(time(NULL));
    // write(n), putchar('\n');
    for (int i = 1, a, b, p, q, j; i <= n; ++i) {
        a = read(), b =read();
        // printf("%d %d\n", a, b);
        if (a == 0) {
            if (flag) insert(rt, b);
            else {
                if (!flag && rt == 0) insert(rt, b), flag = true;
                else {
                    j = inf;
                    p = queryPre(b), q = queryNxt(b);
                    if (p != inf) j = b - p;
                    if (q != inf && q - b < j) j = q - b;
                    if (j != inf) ans = ((long long)ans + j % mod) % mod;
                    if (p != inf && j == b - p) del(rt, p); 
                    else if(q != inf && j == q - b) del(rt, q);
                }
            } 
        } else if (a == 1) {
            if (!flag) insert(rt, b);
            else {
                if (flag && rt == 0) insert(rt, b), flag = false;
                else {
                    j = inf;
                    p = queryPre(b), q = queryNxt(b);
                    if (p != inf) j = b - p;
                    if (q != inf && q - b < j) j = q - b;
                    if (j != inf) ans = ((long long)ans + j % mod) % mod;
                    if (p != inf && j == b - p) del(rt, p); 
                    else if(q != inf && j == q - b) del(rt, q);
                }
            }
        }
    }
    write(ans);
    return 0;
}