HDU 5651 xiaoxin juju needs help
xiaoxin juju needs help
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 665 Accepted Submission(s): 196
Problem Description
As we all known, xiaoxin is a brilliant coder. He knew **palindromic** strings when he was only a six grade student at elementry school. This summer he was working at Tencent as an intern. One day his leader came to ask xiaoxin for help. His leader gave him a string and he wanted xiaoxin to generate palindromic strings for him. Once xiaoxin generates a different palindromic string, his leader will give him a watermelon candy. The problem is how many candies xiaoxin's leader needs to buy?
Input
This problem has multi test cases. First line contains a single integer which represents the number of test cases. For each test case, there is a single line containing a string .
Output
For each test case, print an integer which is the number of watermelon candies xiaoxin's leader needs to buy after mod .
Sample Input
3
aa
aabb
aSample Output
1
2
1Source
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#include <iostream>
#include <string.h>
#include <stdlib.h>
#include <algorithm>
#include <math.h>
#include <stdio.h>
#include <map>
using namespace std;
const __int64 mod=1e9+7;
char a[1005];
int t;
int res[1005];
map<char,int> m;
int a1[1000][1000];
void init()
{
a1[1][1]=1;
for(int i=2;i<=600;i++)
{
for(int j=1;j<=i;j++)
{
if(j==1)
a1[i][j]=1;
else if(j==i)
a1[i][j]=1;
else
a1[i][j]=(a1[i-1][j]+a1[i-1][j-1])%mod;
}
}
}
int main()
{
int t;
scanf("%d",&t);
while(t--)
{
scanf("%s",a);
int len=strlen(a);
m.clear();
int tag=0;
//cout<<m[a[1]]<<endl;
for(int i=0;i<len;i++)
{
m[a[i]]++;
}
int cnt=1;
init();
memset(res,0,sizeof(res));
__int64 sum=0;
for(int i=0;i<len;i++)
{
if(m[a[i]]==-1)
continue;
if(m[a[i]]&1)
tag++;
res[cnt++]=(m[a[i]])/2;
sum+=(m[a[i]])/2;
m[a[i]]=-1;
}
if(tag==1&&(!(len&1)))
{
printf("0\n");
continue;
}
if(tag>=2)
{
printf("0\n");
continue;
}
__int64 num=1;
for(int i=1;i<cnt;i++)
{
num=(num*a1[sum+1][res[i]+1])%mod;
sum-=res[i];
}
printf("%I64d\n",num);
}
return 0;
}腾讯云开发者
