bzoj1689 / P1589 [Usaco2005 Open] Muddy roads 泥泞的路

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<algorithm>
 5 using namespace std;
 6 struct data{int l,r;}a[10002];
 7 bool cmp(const data &A,const data &B){
 8     return A.l<B.l||(A.l==B.l&&A.r>B.r);
 9 }
10 int n,L,tl=-1,ans;
11 int main(){
12     scanf("%d%d",&n,&L);
13     for(int i=1;i<=n;++i)
14         scanf("%d%d",&a[i].l,&a[i].r);
15     sort(a+1,a+n+1,cmp);
16     for(int i=1,q;i<=n;++i){
17         --a[i].r;
18         if(a[i].r<=tl) continue;
19         if(tl<a[i].l){
20             q=(a[i].r-a[i].l)/L;
21             ans+=q; tl=a[i].l-1+q*L;
22             if(tl<a[i].r) ++ans,tl+=L;
23         }else if(tl<a[i].r){
24             q=(a[i].r-tl)/L;
25             ans+=q; tl+=q*L;
26             if(tl<a[i].r) ++ans,tl+=L;
27         }
28     }printf("%d",ans);
29     return 0;
30 }