HDU 3068 Max retrieval (Manacher)

HDU 3068 Max retrieval (Manacher)
Question

A lowercase English character a, B, c... Returns the length of the longest input string in S.
The same string is used for both positive and negative reads, such as aba and abba.

Ideas

Insert special characters into the middle of every two characters in the s string to realize that each input string is an odd number, and then use the manacher algorithm to solve the problem.

Code

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        Using namespace std; const int N = 110009; char s [N], t [N <1]; int p [N <1]; int manacher (int len) {int id = 1, mx = 0; p [0] = 1; for (int I = 1; I 
       
         I) p [I] = min (mx-I, p [2 * id-I]); else p [I] = 1; while (t [I + p [I] = t [I-p [I]) p [I] ++; if (mx <p [I] + I) {mx = p [I] + I; id = I ;}} int ans = p [1]; for (int I = 1; I