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HDU 5676 ztr loves lucky numbers

蛇发女妖 2022-10-18 阅读 112


ztr loves lucky numbers

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 51    Accepted Submission(s): 24


Problem Description

ztr loves lucky numbers. Everybody knows that positive integers are lucky if their decimal representation doesn't contain digits other than 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

Lucky number is super lucky if it's decimal representation contains equal amount of digits 4 and 7. For example, numbers 47, 7744, 474477 are super lucky and 4, 744, 467 are not.

One day ztr came across a positive integer n. Help him to find the least super lucky number which is not less than n.

 


Input

(1≤n≤105) cases

For each cases:

The only line contains a positive integer n(1≤n≤1018). This number doesn't have leading zeroes.

 


Output

For each cases
Output the answer

 


Sample Input


2
4500
47


 


Sample Output


4747
47
把1到10^20中满足条件的全部枚举出来,然后再二分查找就可以了。注意20位最小的44444444447777777777在是超long long int 的只好进行一下特判#include <iostream>
#include <string.h>
#include <stdlib.h>
#include <algorithm>
#include <math.h>
#include <stdio.h>
#include <string>
#include <map>

using namespace std;
#define MAX 600000
typedef __int64 LL;
LL n;
LL a[MAX];
int cnt;
void dfs(LL x,LL y,LL num)
{
if(x==0&&y==0)
{
a[++cnt]=num;
return;
}
if(x>0)
dfs(x-1,y,num*10+4);
if(y>0)
dfs(x,y-1,num*10+7);
}
void fun()
{
a[1]=47;
a[2]=74;
cnt=2;
for(int i=4;i<=18;i+=2)
{
dfs(i/2,i/2,0);
}
}
int main()
{
int t;
scanf("%d",&t);
fun();
sort(a+1,a+cnt+1);
while(t--)
{
scanf("%I64d",&n);
if(n>777777777444444444)
{
cout<<"44444444447777777777"<<endl;
continue;
}
LL l=1,r=cnt;
LL res;
while(l<=r)
{
LL mid=(l+r)/2;
if(a[mid]>=n)
{
res=a[mid];
r=mid-1;
}
else
l=mid+1;
}
printf("%I64d\n",res);
}
return 0;
}


 



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