hdoj5676ztr loves lucky numbers

ztr loves lucky numbers

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 487    Accepted Submission(s): 199

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

There are T(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

2450047

 

Sample Output

474747

#include<iostream>#include<cstdio>#include<cstdlib>#include<cstring>#include<algorithm>#include<queue>#include<list>#include<vector>#include<cmath>using namespace std;const int maxn=1000010;long long ans[maxn],cnt=0;void dfs(long long num,int cnt4,int cnt7,int n){if(cnt4>n/2||cnt7>n/2)return;if(cnt4+cnt7==n&&cnt4==cnt7){ans[cnt++]=num;return;}if(cnt4<=n/2)dfs(num*10+4,cnt4+1,cnt7,n);if(cnt7<=n/2)dfs(num*10+7,cnt4,cnt7+1,n);}int main(){cnt=0;for(long long i=2;i<=18;i+=2){dfs(0,0,0,i);}int t;long long n;scanf("%d",&t);while(t--){scanf("%lld",&n);if(n>777777777444444444ll){printf("44444444447777777777\n");}else printf("%lld\n",ans[lower_bound(ans,ans+cnt,n)-ans]);}return 0;}