Length of the maximum symmetric substring in a string (C + + software engineer Interview question) __c++

Reprint: Please indicate the source, http://blog.csdn.net/zonghongyan314/article/details/41787877, thank you.

Recently read a more interesting algorithm for the length of the largest symmetric substring in the string, share with you.

Idea: Use the next array to prevent a rollback comparison, for example: String str: "ABCXXXXXCBVVVVV", which corresponds to the next array value:

	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14
Str:	A	B	C	X	X	X	X	X	C	B	V	V	V	V	V
Next	1	1	1	1	2	3	4	5	7	9	1	2	3	4	5

The time complexity of the "Dead Knock Class" algorithm is increased to O (n). With KMP next similar O (∩_∩) o~, but unfortunately has not yet understood KMP.

#include <iostream> using namespace std; /**************************************************** ******* @Author Renzi ****2014 year December 7 **************** function: Enter a string
, output the length of the largest symmetric substring in the string for example: "ABACC" returns 3, "a" returns 1,ABB returns 4; Input: String str returns: the length of the maximum symmetric substring of int *****************************************************/int strsymmetriccounts (const char*

STR);
	int main () {char* str= "ABCXXXXXXXXCCCCC";
	printf ("Source string:%s\n", str);
	int len = strsymmetriccounts (str);
	printf ("Maximum symmetric substring length:%d\n", Len);
return 0;
	int strsymmetriccounts (const char* str) {if (str==null) return-1;
	int Len=strlen (str);
	int maxlen=1;
	The int next[30];//next array resembles the next array next[0]=1 in KMP;
	int i=1;
		while (i<len) {int max=1; if ((i-next[i-1]-1) >=0 && str[i]==str[i-next[i-1]-1]) {//rollback compare Max = max > (next[i-1]+2) through next array? Max: (
		NEXT[I-1]+2);
		int k=1;
		while (Str[i]==str[i-k])//If the array of strings is adjacent equal k++;

		max = max > k?max:k; next[i]=max;//assigns the next array cout<< "next[" <<i<< "]=" <<next[i]<< ";

		"<<endl;	   
		if (Next[i]>maxlen) {maxlen=next[i];
	} i++;
return maxlen;  }