Codeforces Beta Round #35 (Div. 2) E. Parade(扫描线)

题目链接

只要会做，周长并，这题肯定有思路。

有个小地方敲错了，细心啊，扫描线，有一段时间没写过了，还有注意排序的问题，很重要。

#include <iostream>
#include <cstdio>
#include <cstring>
#include <vector>
#include <cmath>
#include <algorithm>
using namespace std;
#define LL __int64
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
int que[300000];
int sum[4*300000];
int cnt[4*300000];
int ax[1000101],ay[1000101];
struct node
{
    int h,x,c;
    node(){}
    node(int a,int b,int c):h(a),x(b),c(c){}
    bool operator < (const node &S)const
    {
        if(x == S.x)
        {
            if(c != S.c)
            return c > S.c;
            else if(c == 1)
            return h > S.h;
            else if(c == -1)
            return h < S.h;
        }
        return x < S.x;
    }
}mat[200101];
void pushup(int rt,int l,int r)
{
    if(cnt[rt])
    sum[rt] = que[r+1] - que[l];
    else if(l == r)
    sum[rt] = 0;
    else
    sum[rt] = sum[rt<<1] + sum[rt<<1|1];
}
void update(int L,int R,int c,int l,int r,int rt)
{
    int m;
    if(L <= l&&r <= R)
    {
        cnt[rt] += c;
        pushup(rt,l,r);
        return ;
    }
    m = (l + r)>>1;
    if(L <= m)
    update(L,R,c,lson);
    if(R > m)
    update(L,R,c,rson);
    pushup(rt,l,r);
    return ;
}
int bin(int x,int y)
{
    int str,end,mid;
    str = 0;
    end = y;
    while(str <= end)
    {
        mid = (str+end)/2;
        if(que[mid] == x)
        return mid;
        else if(que[mid] > x)
        end = mid - 1;
        else
        str = mid + 1;
    }
    return mid;
}
int main()
{
    int n,i,h,l,r,num;
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);
    scanf("%d",&n);
    num = 0;
    for(i = 0;i < n;i ++)
    {
        scanf("%d%d%d",&h,&l,&r);
        que[i] = h;
        mat[num++] = node(h,l,1);
        mat[num++] = node(h,r,-1);
    }
    que[n] = 0;
    sort(que,que+n+1);
    sort(mat,mat+num);
    int k = 1;
    for(i = 1;i <= n;i ++)
    {
        if(que[i] != que[i-1])
        que[k++] = que[i];
    }
    int tn = 0,pre = 0;
    for(i = 0;i < num;i ++)
    {
        l = 0;
        r = bin(mat[i].h,k-1) - 1;
        if(l <= r)
        {
            update(l,r,mat[i].c,0,k-1,1);
        }
        if(pre != sum[1])
        {
            ax[tn] = mat[i].x;
            ay[tn++] = pre;
            ax[tn] = mat[i].x;
            ay[tn++] = sum[1];
            pre = sum[1];
        }
    }
    printf("%d
",tn);
    for(i = 0;i < tn;i ++)
    {
        printf("%d %d
",ax[i],ay[i]);
    }
    return 0;
}