65 lines
1.1 KiB
C++
65 lines
1.1 KiB
C++
#include<cstdio>
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#include<cstring>
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#include<string>
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#include<algorithm>
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using namespace std;
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const int maxn=1005;
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char s[maxn];
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int n,dp[maxn][maxn];
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string res[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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while(scanf("%s",s)==1)
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{
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n=strlen(s);
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for(int len=1;len<=n;len++)
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for(int L=0;L+len<=n;L++)
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{
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int R=L+len-1;
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if(L==R)
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{
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dp[L][R]=1;
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res[L][R]=s[L];
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}
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else
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{
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dp[L][R]=dp[L+1][R-1]+(s[L]==s[R]?2:0);
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dp[L][R]=max(dp[L][R],dp[L+1][R]);
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dp[L][R]=max(dp[L][R],dp[L][R-1]);
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res[L][R]="{";
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if(dp[L][R]==dp[L+1][R-1]+(s[L]==s[R]?2:0))
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{
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if(s[L]==s[R])
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res[L][R]=s[L]+res[L+1][R-1]+s[R];
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else
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res[L][R]=res[L+1][R-1];
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}
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if(dp[L][R]==dp[L+1][R])
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res[L][R]=min(res[L][R],res[L+1][R]);
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if(dp[L][R]==dp[L][R-1])
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res[L][R]=min(res[L][R],res[L][R-1]);
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}
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// printf("dp[%d][%d]=%d ",L,R,dp[L][R]);
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// printf("res[%d][%d]=%s\n",L,R,res[L][R].c_str());
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}
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printf("%s\n",res[0][n-1].c_str());
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}
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return 0;
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}
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/*
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Sample Input
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aabbaabb
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computer
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abzla
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samhita
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Sample Output
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aabbaa
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c
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aba
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aha
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*/
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