URAL1133. Fibonacci Sequence（二分）

1133

刚开始还用记忆化推了下公式 后来发现数是非常大的 

二分 然后就是精度错误 中间值会很大

乱七八糟的改

 1 #include <iostream>

 2 #include<cstdio>

 3 #include<cstring>

 4 #include<algorithm>

 5 #include<stdlib.h>

 6 #include<cmath>

 7 #include<vector>

 8 using namespace std;

 9 #define LL long long

10 #define INF 2147483647

11 long double f[3010];

12 int main()

13 {

14     LL i,j,s1,s2,t,n,g;

15     cin>>i>>s1>>j>>s2>>n;

16     i+=1005;j+=1005;n+=1005;

17     if(i>j)

18     {

19         t = i;i = j;j = t;

20         t = s1;s1 = s2; s2 = t;

21     }

22     f[i] = s1;

23     f[j] = s2;

24     if(j!=i+1)

25     {

26         long double low = -INF,high = INF,m;

27         while(low<high)

28         {

29             m = (low+high)/2;

30             f[i+1] = m;

31             for(g = i+2 ; g < j ; g++)

32             {

33                 f[g] = f[g-1]+f[g-2];

34             }

35             long double tt = f[j-1]+f[j-2];

36             if(tt<s2)

37             low = m+1;

38             else if(tt>s2)

39             high = m-1;

40             else low=m,high=m;

41         }

42         f[i+1] = (low+high)/2;

43         for(g = i+2 ; g < j ; g++)

44         {

45             f[g] = f[g-1]+f[g-2];

46         }

47     }

48     if(n<i)

49     {

50         for(g = i-1 ; g >= n ; g--)

51             f[g] = f[g+2]-f[g+1];

52     }

53     else if(n>j)

54     {

55         for(g = j+1 ; g <= n ; g++)

56             f[g] = f[g-1]+f[g-2];

57     }

58     cout<<(LL)f[n]<<endl;

59     return 0;

60 }

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