Substring

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Substring

时间限制：1000 ms | 内存限制：65535 KB

描述

You are given a string input. You are to find the longest substring of input such that the reversal of the substring is also a substring of input. In case of a tie, return the string that occurs earliest in input.

Note well: The substring and its reversal may overlap partially or completely. The entire original string is itself a valid substring . The best we can do is find a one character substring, so we implement the tie-breaker rule of taking the earliest one first.

输入

The first line of input gives a single integer, 1 ≤ N ≤ 10, the number of test cases. Then follow, for each test case, a line containing between 1 and 50 characters, inclusive. Each character of input will be an uppercase letter ('A'-'Z').

输出

Output for each test case the longest substring of input such that the reversal of the substring is also a substring of input

样例输入

3                   ABCABAXYZXCVCX

样例输出

ABAXXCVCX

来源

第四届河南省程序设计大赛

上传者 张云聪 思路：用二维的矩阵来做。。 #include<iostream>#include<string.h>using namespace std;int main(){ int num[51][51]; char a[51],b[51]; int T,i,j,k,len,max,x,y,start; cin>>T; while(T--) { memset(num,0,sizeof(num)); k=0; max=0; cin>>a; //ABCABA len=strlen(a); for(i=len-1;i>=0;i--) { b[k++]=a[i]; } b[k]='\0'; for(i=1;i<=len;i++) { for(j=1;j<=len;j++) { if(a[i-1]==b[j-1]) { num[i][j]=num[i-1][j-1]+1; if(num[i][j]>max) { max=num[i][j];//max最大的长度 x=i; y=j; } } } } start=x-max; for(i=start;i<start+max;i++) cout<<a[i]; cout<<endl; }return 0;}

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