POJ2437 Muddy roads

 1 #include<iostream>
 2 #include<algorithm>
 3 #include<cstring>
 4 #include<cstdio>
 5 #include<cmath>
 6 using namespace std;
 7 const int mxn=12000;
 8 struct wd{
 9     int x,y;
10     bool operator < (const wd rhd){
11         return x<rhd.x;
12     }
13 }a[mxn];
14 int n,L;
15 int main(){
16     scanf("%d%d",&n,&L);
17     int i,j;
18     for(i=1;i<=n;i++){
19         scanf("%d%d",&a[i].x,&a[i].y);
20     }
21     sort(a+1,a+n+1);
22     int cnt=0;
23     int now=0;
24     for(i=1;i<=n;i++){
25         now=max(now,a[i].x);//开始铺
26         while(now<a[i].y){
27             now+=L;
28             cnt++;
29         }
30     }
31     printf("%d\n",cnt);
32     return 0;
33 }