pat1040. Longest symmetric String (25)

1040. Longest symmetric String (25) time limit of MS memory limit 65536 KB code length limit 16000 B procedure StandardAuthor Chen, Yue

Given A string, you is supposed to output the length of the longest symmetric sub-string. For example, given ' is pat&tap symmetric? ', the longest symmetric sub-string is ' s pat&tap s ', hence you must OUTP UT 11.

Input Specification:

Each input file contains one test case which gives a non-empty string of length No. more than 1000.

Output Specification:

For each test case, simply print the maximum length in a line.

Sample Input:

Is Pat&tap symmetric?

Sample Output:

11

Submit Code

Method One: Insert invalid characters, traverse once.

1#include <cstdio>2#include <algorithm>3#include <iostream>4#include <cstring>5#include <queue>6#include <vector>7#include <cmath>8#include <string>9#include <map>Ten#include <Set> One using namespacestd; A intdp[20005]; - intMain () { -     //freopen ("D:\\input.txt", "R", stdin); the     //scanf ("%s", s); -     strings; - getline (cin,s); -  +     //cout<<s<<endl; -  +     inti,j=0, k,count=0; Adp[j++]=-1; at      for(i=0; I<s.length (); i++){ -Dp[j++]=s[i];//Hash -dp[j++]=-1; -     } -  -     //cout<<j<<endl; in  -      for(i=1; i<j;i++) {//I start from 1!!  to         intf=i-1, b=i+1; +          while(f>=0&&b<j&&dp[f]==Dp[b]) { -f--; theb++; *         } $         if(count<b-f-1){Panax Notoginsengcount=b-f-1; -             //cout<<count<<endl; the         } +     } Aprintf"%d\n", count/2);//here can be divided into the center for-1 and the normal number of 2 case discussion the     return 0; +}

Method Two: Sub-parity discussion:

1#include <cstdio>2#include <algorithm>3#include <iostream>4#include <cstring>5#include <queue>6#include <vector>7#include <cmath>8#include <string>9#include <map>Ten#include <Set> One using namespacestd; A intMain () { -     //freopen ("D:\\input.txt", "R", stdin); -     //scanf ("%s", s); the     strings; - getline (cin,s); -  -     //cout<<s<<endl; +  -     intI,j,k,count=0; +      for(i=0; I<s.length (); i++){ A         intf=i,b=i; at          while(f>=0&&b<s.length () &&s[f]==S[b]) { -f--; -b++; -         } -         if(count<b-f-1){ -count=b-f-1; in         } -f=i; tob=i+1; +          while(f>=0&&b<s.length () &&s[f]==S[b]) { -f--; theb++; *         } $         if(count<b-f-1){Panax Notoginsengcount=b-f-1; -         } the     } +printf"%d\n", count); A     return 0; the}

pat1040. Longest symmetric String (25)