8.4总结

其实8.4是在昨天，只不过昨天我电脑出了点问题，输入法死活调不出来。

主要做了2件事，一是刷KD—tree的板子题，二是自己YY一个替罪羊树的板子

KD-tree：由于只刷了板子题，还没什么想法

替罪羊：其实还是有点子思维量的，思想很简单，但实现要仔细斟酌，替罪羊树最核心的

就是它的重构函数，选择适当的时间及适当的范围进行重构，从而使得子树保持平衡，便于操作

其实感觉数组版应该比较好打，然而旁边几个人一直劝我打指针，我又不会什么骚操作，

然后就莫名奇妙加了好多行判空;

#include <bits/stdc++.h>
#define N 1000006
#define A 0.75
#define puts puts
using namespace std;
struct sheep {
    int val, fsz, tsz, cnt;
    sheep *ch[2], *fa;
} * rt;
int tot, alr;
sheep *re[N];
bool pingheng(sheep *g) {
    return (g->ch[0] ? g->ch[0]->fsz : 0) <= g->fsz * A || (g->ch[1] ? g->ch[1]->fsz : 0) <= g->fsz * A;
}
void update(sheep *p) {
    p->fsz = p->tsz = p->cnt;
    if (p->ch[0] != NULL)
        p->fsz += p->ch[0]->fsz, p->tsz += p->ch[0]->tsz;
    if (p->ch[1] != NULL)
        p->fsz += p->ch[1]->fsz, p->tsz += p->ch[1]->tsz;
}
void getup(sheep *g) {
    if (g->ch[0] != NULL)
        getup(g->ch[0]);
    if (g->cnt)
        re[++alr] = g;
    if (g->ch[1] != NULL)
        getup(g->ch[1]);
}
sheep *build(int l, int r, sheep *f) {
    const int mid = l + r >> 1;
    if (l != mid)
        re[mid]->ch[0] = build(l, mid - 1, re[mid]);
    else
        re[mid]->ch[0] = NULL;
    if (r != mid)
        re[mid]->ch[1] = build(mid + 1, r, re[mid]);
    else
        re[mid]->ch[1] = NULL;
    update(re[mid]);
    re[mid]->fa = f;
    return re[mid];
}
sheep *rebuild(sheep *g, sheep *f) {
    alr = 0;
    getup(g);
    return build(1, alr, f);
}
void insert2(int x, sheep *g) {
    //    puts("boom at insert2");
    ++g->fsz;
    ++g->tsz;
    if (g->val < x) {
        if (g->ch[1] == NULL) {
            g->ch[1] = new sheep();
            g->ch[1]->fa = g;
            g->ch[1]->val = x, g->ch[1]->fsz = g->ch[1]->tsz = g->ch[1]->cnt = 1;
            return;
        }
        insert2(x, g->ch[1]);
    } else if (g->val == x) {
        ++g->cnt;
    } else {
        if (g->ch[0] == NULL) {
            g->ch[0] = new sheep();
            g->ch[0]->fa = g;
            g->ch[0]->val = x, g->ch[0]->fsz = g->ch[0]->tsz = g->ch[0]->cnt = 1;
            return;
        }
        insert2(x, g->ch[0]);
    }

    if (g == rt) {
        if (!pingheng(g)) {
            sheep *f = new sheep();
            rt = rebuild(g, f);
            rt->fa = NULL;
        }
        return;
    }
    if (!pingheng(g) && pingheng(g->fa)) {
        sheep *f = g->fa;
        if (f->ch[0] == g)
            f->ch[0] = rebuild(g, f);
        else
            f->ch[1] = rebuild(g, f);
    }
    update(g);
}
void insert(int p) {
    if (rt == NULL) {
        rt = new sheep(), rt->val = p, rt->fsz = rt->tsz = rt->cnt = 1;
        return;
    }
    insert2(p, rt);
}
sheep *getval(int rk) {
    int ans = 0;
    sheep *g = rt;
    while (1) {
        if (g->cnt && rk >= (g->ch[0] == NULL ? 0 : g->ch[0]->tsz) + 1 &&
            rk <= (g->ch[0] == NULL ? 0 : g->ch[0]->tsz) + g->cnt)
            return g;
        if (rk > (g->ch[0] ? g->ch[0]->tsz : 0) + g->cnt) {
            rk -= (g->ch[0] ? g->ch[0]->tsz : 0) + g->cnt;
            g = g->ch[1];
        } else
            g = g->ch[0];
    }
}
int getrank(int x) {
    int ans = 0;
    sheep *g = rt;
    while (1) {
        if (g->cnt && x == g->val)
            return ans + (g->ch[0] ? g->ch[0]->tsz : 0) + 1;
        if (x > g->val) {
            ans += (g->ch[0] ? g->ch[0]->tsz : 0) + g->cnt;
            g = g->ch[1];
        } else
            g = g->ch[0];
    }
}
sheep *getzz(int x) {
    int ans = 0;
    sheep *g = rt;
    while (1) {
        if (g->cnt && x == g->val)
            return g;
        if (x > g->val)
            g = g->ch[1];
        else
            g = g->ch[0];
    }
}
void del(sheep *p) {
    --p->tsz;
    --p->cnt;
    while (p != rt) {
        p = p->fa;
        update(p);
    }
}
int main() {
    int n, x, p;
    scanf("%d", &n);
    while (n--) {
        scanf("%d%d", &p, &x);
        switch (p) {
            case 1: {
                insert(x);
                break;
            }
            case 2: {
                del(getzz(x));
                break;
            }
            case 3: {
                insert(x);
                printf("%d
", getrank(x));
                del(getzz(x));
                break;
            }
            case 4: {
                printf("%d
", getval(x)->val);
                break;
            }
            case 5: {
                insert(x);
                printf("%d
", getval(getrank(x) - 1)->val);
                del(getzz(x));
                break;
            }
            case 6: {
                insert(x);
                printf("%d
", getval(getrank(x) + getzz(x)->cnt)->val);
                del(getzz(x));
                break;
            }
        }
    }
}

自己的板子，有错误还请各位dalao指正;

现在距NOIP还有94天，今天上午模拟赛后就要分机房了，我刚好在一机房和二机房的分界线出

现在慌的一批，成败在此一举，我更应调整心态，积极面对，留在第一机房是我的实力，不能留

也是一种经历。