HDU 4004 The Frog's Games(二分)

题目链接

题意理解的有些问题。

 1 #include <iostream>

 2 #include<cstdio>

 3 #include<cstring>

 4 #include<algorithm>

 5 using namespace std;

 6 #define LL __int64

 7 LL p[501001];

 8 int n;

 9 int judge(int x,int m)

10 {

11     int pre = 0,num = 0,i;

12     for(i = 0;i <= n;i ++)

13     {

14         if(p[i] - pre <= x)

15         ;

16         else

17         {

18             num ++;

19             pre = p[i-1];

20         }

21     }

22     if(num + 1 > m)

23     return 0;

24     else

25     return 1;

26 }

27 int main()

28 {

29     int m,i,l;

30     LL str,mid,end,minz;

31     while(scanf("%d%d%d",&l,&n,&m)!=EOF)

32     {

33         for(i = 0; i < n; i ++)

34             scanf("%I64d",&p[i]);

35         sort(p,p+n);

36         if(n == 0||m == 1)

37         {

38             printf("%d\n",l);

39             continue;

40         }

41         p[n] = l;

42         minz = p[0];

43         for(i = 0;i < n;i ++)

44         {

45             minz = max(minz,p[i+1]-p[i]);

46         }

47         str = minz;end = l;

48         while(str < end)

49         {

50             mid = (str+end)/2;

51             if(judge(mid,m) == 0)

52             str = mid + 1;

53             else

54             end = mid;

55         }

56         printf("%I64d\n",str);

57     }

58     return 0;

59 }