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。

  1 #include <iostream>

  2 #include <cstdio>

  3 #include <cstring>

  4 #include <vector>

  5 #include <cmath>

  6 #include <algorithm>

  7 using namespace std;

  8 #define LL __int64

  9 #define lson l,m,rt<<1

 10 #define rson m+1,r,rt<<1|1

 11 int que[300000];

 12 int sum[4*300000];

 13 int cnt[4*300000];

 14 int ax[1000101],ay[1000101];

 15 struct node

 16 {

 17     int h,x,c;

 18     node(){}

 19     node(int a,int b,int c):h(a),x(b),c(c){}

 20     bool operator < (const node &S)const

 21     {

 22         if(x == S.x)

 23         {

 24             if(c != S.c)

 25             return c > S.c;

 26             else if(c == 1)

 27             return h > S.h;

 28             else if(c == -1)

 29             return h < S.h;

 30         }

 31         return x < S.x;

 32     }

 33 }mat[200101];

 34 void pushup(int rt,int l,int r)

 35 {

 36     if(cnt[rt])

 37     sum[rt] = que[r+1] - que[l];

 38     else if(l == r)

 39     sum[rt] = 0;

 40     else

 41     sum[rt] = sum[rt<<1] + sum[rt<<1|1];

 42 }

 43 void update(int L,int R,int c,int l,int r,int rt)

 44 {

 45     int m;

 46     if(L <= l&&r <= R)

 47     {

 48         cnt[rt] += c;

 49         pushup(rt,l,r);

 50         return ;

 51     }

 52     m = (l + r)>>1;

 53     if(L <= m)

 54     update(L,R,c,lson);

 55     if(R > m)

 56     update(L,R,c,rson);

 57     pushup(rt,l,r);

 58     return ;

 59 }

 60 int bin(int x,int y)

 61 {

 62     int str,end,mid;

 63     str = 0;

 64     end = y;

 65     while(str <= end)

 66     {

 67         mid = (str+end)/2;

 68         if(que[mid] == x)

 69         return mid;

 70         else if(que[mid] > x)

 71         end = mid - 1;

 72         else

 73         str = mid + 1;

 74     }

 75     return mid;

 76 }

 77 int main()

 78 {

 79     int n,i,h,l,r,num;

 80     freopen("input.txt","r",stdin);

 81     freopen("output.txt","w",stdout);

 82     scanf("%d",&n);

 83     num = 0;

 84     for(i = 0;i < n;i ++)

 85     {

 86         scanf("%d%d%d",&h,&l,&r);

 87         que[i] = h;

 88         mat[num++] = node(h,l,1);

 89         mat[num++] = node(h,r,-1);

 90     }

 91     que[n] = 0;

 92     sort(que,que+n+1);

 93     sort(mat,mat+num);

 94     int k = 1;

 95     for(i = 1;i <= n;i ++)

 96     {

 97         if(que[i] != que[i-1])

 98         que[k++] = que[i];

 99     }

100     int tn = 0,pre = 0;

101     for(i = 0;i < num;i ++)

102     {

103         l = 0;

104         r = bin(mat[i].h,k-1) - 1;

105         if(l <= r)

106         {

107             update(l,r,mat[i].c,0,k-1,1);

108         }

109         if(pre != sum[1])

110         {

111             ax[tn] = mat[i].x;

112             ay[tn++] = pre;

113             ax[tn] = mat[i].x;

114             ay[tn++] = sum[1];

115             pre = sum[1];

116         }

117     }

118     printf("%d\n",tn);

119     for(i = 0;i < tn;i ++)

120     {

121         printf("%d %d\n",ax[i],ay[i]);

122     }

123     return 0;

124 }