26 lines
557 B
C++
26 lines
557 B
C++
#include<cstdio>
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#include<cstring>
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#include<algorithm>
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using namespace std;
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typedef long long LL;
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const LL mod=1e9;
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const int maxn=305;
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int n; char s[maxn]; LL f[maxn][maxn];
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int main()
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{
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#ifdef local
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freopen("pro.in","r",stdin);
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#endif
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scanf("%s",s+1); n=strlen(s+1);
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for(int i=1;i<=n;i++) f[i][i]=1;
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for(int len=2;len<=n;len++)
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for(int i=1;i+len-1<=n;i++)
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{
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int j=i+len-1;
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if(s[i]!=s[j]) continue;
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for(int k=i+2;k<=j-2;k++) (f[i][j]+=f[i+1][k-1]*f[k][j])%=mod;
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(f[i][j]+=f[i+1][j-1])%=mod;
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}
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printf("%lld\n",f[1][n]);
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return 0;
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} |