HDU 5976 Detachment 【貪心】 (2016ACM/ICPC亞洲區大連站)
阿新 • • 發佈:2019-02-13
Detachment
Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 570 Accepted Submission(s): 192Problem Description In a highly developed alien society, the habitats are almost infinite dimensional space.
In the history of this planet,there is an old puzzle.
You have a line segment with x units’ length representing one dimension.The line segment can be split into a number of small line segments: a
1.Two different small line segments cannot be equal ( ai≠aj when i≠j).
2.Make this multidimensional space size s as large as possible (s= a
Now can you solve this question and find the maximum size of the space?(For the final number is too large,your answer will be modulo 10^9+7)
Input The first line is an integer T,meaning the number of test cases.
Then T lines follow. Each line contains one integer x.
1≤T≤10^6, 1≤x≤10^9
Output Maximum s you can get modulo 10^9+7. Note that we wants to be greatest product before modulo 10^9+7.
Sample Input 1 4
Sample Output 4
Source
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題目連結:
題目大意:
給一個數N(N<=109),讓你把它拆成若干各不相同的數Ai,ΣAi=N,要求ΠAi(累乘)最大。
題目思路:
【貪心】
首先肯定要把位數拆的儘量多,手寫了20以內的拆法。
發現以2為首相的遞增序列累乘最大,所以我的想法就是把N拆成2+3+...+x<=n,
先找到x,之後算一下n還多了多少,就把後面依次+1,變成2+3+...+y+(y+2)+(y+3)+...+(x+1)。
這時候它們的累乘是最大的。
(特殊情況是從2到x都加1之後還剩餘1,這時候把最後一項再加1,變成3+4+...+x+(x+2)
//
//by coolxxx
/*
#include<iostream>
#include<algorithm>
#include<string>
#include<iomanip>
#include<map>
#include<stack>
#include<queue>
#include<set>
#include<bitset>
#include<memory.h>
#include<time.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
//#include<stdbool.h>
#define min(a,b) ((a)<(b)?(a):(b))
#define max(a,b) ((a)>(b)?(a):(b))
#define swap(a,b) ((a)^=(b),(b)^=(a),(a)^=(b))
*/
#include<bits/stdc++.h>
#pragma comment(linker,"/STACK:1024000000,1024000000")
#define abs(a) ((a)>0?(a):(-(a)))
#define lowbit(a) (a&(-a))
#define sqr(a) ((a)*(a))
#define mem(a,b) memset(a,b,sizeof(a))
#define eps (1e-8)
#define J 10000
#define mod 1000000007
#define MAX 0x7f7f7f7f
#define PI 3.14159265358979323
#define N 45004
using namespace std;
typedef long long LL;
double anss;
LL aans;
int cas,cass;
int n,m,lll,ans;
LL a[N],ni[N];
LL mi(LL x,LL y)
{
LL z=1;
while(y)
{
if(y&1)z=(z*x)%mod;
x=(x*x)%mod;
y>>=1;
}
return z;
}
void init()
{
int i;
a[1]=1;
ni[1]=1;
for(i=2;i<N;i++)
{
a[i]=(a[i-1]*i)%mod;
ni[i]=(-(mod/i)*a[mod%i])%mod;
}
}
int main()
{
#ifndef ONLINE_JUDGE
freopen("1.txt","r",stdin);
// freopen("2.txt","w",stdout);
#endif
int i,j,k;
int x,y,z;
init();
for(scanf("%d",&cass);cass;cass--)
// for(scanf("%d",&cas),cass=1;cass<=cas;cass++)
// while(~scanf("%s",s))
// while(~scanf("%d%d",&n,&m))
{
scanf("%d",&n);
if(n<5)
{
printf("%d\n",n);
continue;
}
m=n+n+2;
LL l,r,mid;
l=2;r=45000;
while(l<r)
{
mid=(l+r+1)>>1;
if(mid*mid+mid<=m)l=mid;
else r=mid-1;
}
m-=l*l+l;
m/=2;
if(m==l)
{
aans=a[l]*(l+2)%mod*mi(2,mod-2)%mod;
}
else
{
x=l+1-m;
aans=a[l+1]*mi(x,mod-2)%mod;
}
printf("%lld\n",aans);
}
return 0;
}
/*
//
//
*/