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

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stdlib.h>
#include<cmath>
#include<vector>
using namespace std;
#define LL long long
#define INF 2147483647
long double f[3010];
int main()
{
    LL i,j,s1,s2,t,n,g;
    cin>>i>>s1>>j>>s2>>n;
    i+=1005;j+=1005;n+=1005;
    if(i>j)
    {
        t = i;i = j;j = t;
        t = s1;s1 = s2; s2 = t;
    }
    f[i] = s1;
    f[j] = s2;
    if(j!=i+1)
    {
        long double low = -INF,high = INF,m;
        while(low<high)
        {
            m = (low+high)/2;
            f[i+1] = m;
            for(g = i+2 ; g < j ; g++)
            {
                f[g] = f[g-1]+f[g-2];
            }
            long double tt = f[j-1]+f[j-2];
            if(tt<s2)
            low = m+1;
            else if(tt>s2)
            high = m-1;
            else low=m,high=m;
        }
        f[i+1] = (low+high)/2;
        for(g = i+2 ; g < j ; g++)
        {
            f[g] = f[g-1]+f[g-2];
        }
    }
    if(n<i)
    {
        for(g = i-1 ; g >= n ; g--)
            f[g] = f[g+2]-f[g+1];
    }
    else if(n>j)
    {
        for(g = j+1 ; g <= n ; g++)
            f[g] = f[g-1]+f[g-2];
    }
    cout<<(LL)f[n]<<endl;
    return 0;
}