http://www.lydsy.com/JudgeOnline/problem.php?id=2300

終於對了。。。

平衡樹又寫掛了。。。不要忘記清空原先的root和修改root。。。

#include<bits/stdc++.h>
using namespace std;
const int N = 200010;
const double eps = 1e-8;
struct query {
    int x, opt;
} q[N];
struct data {
    double x, y; int cut;
} a[N];
int m, Q, len;
double ans[N];
 
double ans1, n;
namespace splaytree
{
    int root;
    int child[N][2], fa[N];
    void zig(int x)
    {
        int y = fa[x]; 
        fa[x] = fa[y]; child[fa[x]][child[fa[x]][1] == y] = x;
        child[y][0] = child[x][1]; fa[child[x][1]] = y;
        fa[y] = x; child[x][1] = y;
    }
    void zag(int
 
 x)
    {
        int y = fa[x]; 
        fa[x] = fa[y]; child[fa[x]][child[fa[x]][1] == y] = x;
        child[y][1] = child[x][0]; fa[child[x][0]] = y;
        fa[y] = x; child[x][0] = y;
    }
    void splay(int x, int t)
    {
        while(fa[x] != t)
        {
            int y = fa[x], z = fa[y];
            
 
if(z == t) 
            {
                child[y][0] == x ? zig(x) : zag(x); break;
            }
//            child[y][0] == x ? zig(x) : zag(x);
//            child[z][0] == x ? zig(x) : zag(x);
            else if(y == child[z][0] && x == child[y][0]) { zig(y); zig(x); }
              else if(y == child[z][1] && x == child[y][1]) { zag(y); zag(x); }
               else if(y == child[z][0] && x == child[y][1]) { zag(x); zig(x); }
            else if(y == child[z][1] && x == child[y][0]) { zig(x); zag(x); }
        }
        if(!t) root = x;
    }
    void add(data t, int k)
    {
        if(!root) { root = k; return; }
        int now = root;
        while(1) 
        {
            if(!child[now][t.x > a[now].x]) 
            {
                fa[k] = now; child[now][t.x > a[now].x] = k;
                splay(k, 0); return;
            } 
            now = child[now][t.x > a[now].x];
        }
    }
    void del(int x)
    {
        splay(x, 0);
        if(child[x][0] * child[x][1] == 0) 
        {
            root = child[x][0] + child[x][1];
            fa[root] = fa[x] = child[x][0] = child[x][1] = 0; return; 
        }
        int now = child[x][1]; 
        while(child[now][0]) now = child[now][0];
        fa[child[x][0]] = now; child[now][0] = child[x][0]; 
        root = child[x][1]; fa[root] = fa[x] = child[x][0] = child[x][1] = 0;
        splay(now, 0);
    }
    int Pre(int x)
    {    
        splay(x, 0);
        x = child[x][0];
        if(!x) return 0;
        while(child[x][1]) x = child[x][1];
        return x;
    }
    int Next(int x)
    {
        splay(x, 0); 
        x = child[x][1];
        if(!x) return 0;
        while(child[x][0]) x = child[x][0]; 
        return x;
    }
    double slope(int x, int y)
    {
        return (a[y].y - a[x].y) / (a[y].x - a[x].x);
    }
    double sqr(double x)
    {
        return x * x;
    } 
    double dis(int x, int y) 
    {
        if(!x || !y) return 0;
        return sqrt(sqr(a[x].x - a[y].x) + sqr(a[x].y - a[y].y));
    }
    void insert(data t, int x)
    {
        add(t, x); 
        int pre = Pre(x), nxt = Next(x); 
        ans1 += dis(x, pre) + dis(x, nxt) - dis(nxt, pre);
        if(!pre || !nxt) return;
        splay(pre, x); splay(nxt, x);
        if(slope(pre, x) - slope(x, nxt) <= eps) { ans1 -= dis(x, pre) + dis(x, nxt) - dis(pre, nxt); del(x); return; }
        int ppre = Pre(pre), nnxt = Next(nxt);
        while(ppre && slope(x, pre) - slope(pre, ppre) >= eps)  
        { 
            ans1 -= dis(pre, x) + dis(pre, ppre) - dis(x, ppre);
            del(pre); pre = ppre; ppre = Pre(pre); 
        } 
        while(nnxt && slope(x, nxt) - slope(nxt, nnxt) <= eps)  
        { 
            ans1 -= dis(nxt, x) + dis(nxt, nnxt) - dis(x, nnxt);
            del(nxt); nxt = nnxt; nnxt = Next(nxt); 
        } 
    }
} using namespace splaytree;
int main()
{
//    freopen("defense1.in", "r", stdin);
//    freopen("defense.out", "w", stdout);
    scanf("%lf%lf%lf%d", &n, &a[2].x, &a[2].y, &m); m += 3;
    a[3].x = n; a[3].y = 0;
    for(int i = 4; i <= m; ++i) scanf("%lf%lf", &a[i].x, &a[i].y);
    scanf("%d", &Q);
    for(int i = 1; i <= Q; ++i) 
    {
        scanf("%d", &q[i].opt);
        if(q[i].opt == 1) 
        {
            scanf("%d", &q[i].x);
            a[q[i].x + 3].cut = 1;
        }
    }
    len = 0;
    for(int i = 1; i <= m; ++i) if(!a[i].cut) insert(a[i], i);
    for(int i = Q; i; --i) 
        if(q[i].opt == 1) insert(a[q[i].x + 3], q[i].x + 3);
        else if(q[i].opt == 2) ans[++len] = ans1;
    for(int i = len; i; --i) printf("%.2f\n", ans[i]);    
//    fclose(stdin); fclose(stdout);
    return 0;
}

bzoj2300