1191 X axis dyeing, 1191 X axis

1191 X axis dyeing, 1191 X axis
1191 X axis Dyeing

 

Time Limit: 1 s space limit: 128000 KB title level: Gold Title Description Description

There are N points on a number axis, which are 1 ~ N. At first, all vertices were dyed black. Next
We perform M operations and perform I operations to dye the points [Li, Ri] White. Output after each operation is executed
The number of remaining black points.

Input description Input Description

Enter N and M in a row. The following M rows have two numbers in each row: Li and Ri.

Output description Output Description

Output M rows, indicating the number of remaining black points after each operation.

Sample Input Sample Input

10 3
3 3
5 7
2 8

Sample output Sample Output

9
6
3

Data range and prompt Data Size & Hint

Data restrictions
1 <= N <= 30%, 1 <= M <= 2000
1 <= Li <= Ri <= N <= 200000,1 <= M <= 100%

CATEGORY tag Tags click here to expandBare line segment tree. Be sure to remember that if the entire range is 0, you must return.

 1 #include<iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include<cmath> 5 using namespace std; 6 const int MAXN=200001; 7 void read(int & n) 8 { 9     char c='+';int x=0;int flag=0;10     while(c<'0'||c>'9')11     {    if(c=='-')    flag=1;    c=getchar();    }12     while(c>='0'&&c<='9')13     {    x=x*10+(c-48);    c=getchar();}14     flag==1?n=-x:n=x;15 }16 int n,m;17 struct node18 {19     int l,r,w;20 }tree[MAXN*4];21 void update(int k)22 {23     tree[k].w=tree[k<<1].w+tree[k<<1|1].w;24 }25 void build_tree(int ll,int rr,int k)26 {27     28     tree[k].l=ll;tree[k].r=rr;29     if(ll==rr)30     {31         tree[k].w=1;32         return ;33     }    34     int mid=(ll+rr)>>1;35     build_tree(ll,mid,k<<1);36     build_tree(mid+1,rr,k<<1|1);37     update(k);38 }39 void interval_change(int k,int ql,int qr)40 {41     if(tree[k].w==0)42     return ;43     if(ql<=tree[k].l&&qr>=tree[k].r)44     {45         tree[k].w=0;46         return ;47     }48     int mid=(tree[k].l+tree[k].r)>>1;49     if(ql<=mid)50         interval_change(k<<1,ql,qr);51     if(qr>mid)52         interval_change(k<<1|1,ql,qr);53     update(k);54 }55 int main()56 {57     read(n);read(m);58     build_tree(1,n,1);59     for(int i=1;i<=m;i++)60     {61         int x,y;62         read(x);read(y);63         interval_change(1,x,y);64         printf("%d\n",tree[1].w);65     }66     return 0;67 }