贪心/poj 2437 Muddy roads

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 using namespace std;
 5 struct node
 6 {
 7     int st,ed;
 8 };
 9 node a[10010];
10 
11 int n,L,ans,pre;
12 
13 bool cmp(node x,node y)
14 {
15     return x.st<y.st;
16 }
17 
18 int main()
19 {
20     while (scanf("%d%d",&n,&L)!=EOF)
21     {
22         for (int i=1;i<=n;i++) scanf("%d%d",&a[i].st,&a[i].ed);
23         sort(a+1,a+n+1,cmp);
24         ans=0;
25         pre=-9999999;
26         for (int i=1;i<=n;i++)
27         {
28             if (pre<=a[i].st)
29             {
30                 int len=a[i].ed-a[i].st;
31                 int sum=(len+L-1)/L;
32                 ans+=sum;
33                 pre=a[i].st+sum*L;
34             }
35             else if (pre>a[i].st)
36             {
37                 int len=a[i].ed-pre;
38                 int sum=(len+L-1)/L;
39                 ans+=sum;
40                 pre+=sum*L;
41             }
42         }
43         printf("%d\n",ans);
44     }
45     return 0;
46 }