Codevs1299 切水果

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<algorithm>
 4 #include<cstring>
 5 #define ls l,mid,rt<<1
 6 #define rs mid+1,r,rt<<1|1
 7 using namespace std;
 8 const int mxn=800000;
 9 struct node{
10     int sum;
11     bool dec;
12 }t[mxn*4];
13 int n,m;
14 void Build(int l,int r,int rt){//建树 
15     if(l==r){t[rt].sum=1;return;}
16     int mid=(l+r)>>1;
17     Build(ls);Build(rs);
18     t[rt].sum=t[rt<<1].sum+t[rt<<1|1].sum;
19     return;
20 }
21 void cut(int L,int R,int l,int r,int rt){//区间清零 
22     if(t[rt].dec){
23 //        t[rt].dec=0;//这步加上话会WA，有些奇怪 
24         t[rt].sum=0;
25         t[rt<<1].dec=t[rt<<1|1].dec=1;
26         return;
27     }
28     if(L<=l && r<=R){
29         t[rt].sum=0;t[rt].dec=1;return;
30     }
31     int mid=(l+r)>>1;
32     if(L<=mid)cut(L,R,ls);
33     if(R>mid)cut(L,R,rs);
34     t[rt].sum=t[rt<<1].sum+t[rt<<1 |1].sum;
35     return;
36 }
37 int main(){
38     scanf("%d%d",&n,&m);
39     int i,j;
40     Build(1,n,1);
41     int x,y;
42     for(i=1;i<=m;i++){
43         scanf("%d%d",&x,&y);
44         cut(x,y,1,n,1);
45         printf("%d\n",t[1].sum);
46     }
47     return 0;
48 }