Manacher algorithm for processing the longest palindrome string (ii)

In the previous article "manacher algorithm processing the longest palindrome substring (a)" explained the principle of the Manacher algorithm, and then to the algorithm, the program in the Leetcode of the longest palindrome string passed. First of all, the Manacher algorithm maintains 3 variables. An array named radius[i], which represents the radius of the palindrome string with the center bearing i, such as abcdcba, the subscript of character D is 4, then his radius[4]=3, the radius of a 0 of a is radius[0]=0, that is, the center axis is not Considered. An IDX indicates the last palindrome with an IDX as the central Axis. If a palindrome centered on I is in a palindrome centered on the Idx. The IDX is not updated, otherwise after processing radius[i], the IDX needs to be updated to I. The last RAD maintenance idx can contain the largest range of the next word Poute, in fact when i+radius[i] to reach rad the IDX needs to be updated.

Code:

 1 class Solution {2 Public:3 string longestpalindrome (string s) {4 int n=s.size (); 5 string str ( n+1, ' 0 '); 6 bool flag=1; 7 int j=0; 8 int maxidx=0;            9 for (int I=0;i<2*n+1;i++) {ten if (flag) {str[i]= ' # '; flag=false;13 }else{14 str[i]=s[j++];15 flag=true;16}17}18 vector&             lt;int> radius (2*n+1,0), int idx=0;20 int rad=1;21 for (int i=1;i<2*n+1;i++) {22 If (i>=rad) {forceextend (str,radius,idx,rad,i); maxidx= (radius[i]>radius[maxidx] I:maxidx);}else if (i<rad) {n int j=2*idx-i;27 int Idx_radius=idx-radius [idx];28 int j_radius=j-radius[j];29 if (j_radius>idx_radius) {rad Ius[i]=radius[j];31}32 else if (j_radiUs<idx_radius) {radius[i]=idx+radius[idx]-i;34}else{35 Radiu s[i]=idx+radius[idx]-i;36 int count=1;37 while ((i+radius[i]+count) <=str.size () & amp;& (i-radius[i]-count) >=0&&str[i+radius[i]+count]==str[i-radius[i]-count]) Coun                         t++;39 radius[i]+= (count-1); if (i+radius[i]>=rad) {41 idx=i;42 rad=i+count;43}44}45 maxidx= (radius [i]>radius[maxidx]?i:maxidx];}47}49 string ret=getmaxsubstring (str,maxid x,radius[maxidx]), ret;51}52 void forceextend (const string& str, vector<int>& Radi Us,int &idx,int &rad,const int k) {int count=1;54 while (k-count) >=0&& (k+count) <st R.size () &&str[k-Count]==str[k+count]) {count++;56}57 radius[k]=count-1;58 if (k+radius[k]>=rad) {5 9 idx=k;60 rad=k+count;61}62}63 string getmaxsubstring (const string &str,con             St int K,const int r) {0 string ret (r, ' '); n-j=0;66 for (int i=k-r+1;i<=k+r;i+=2) {67 ret[j++]=str[i];68}69 return ret;70}71 72};

Manacher algorithm for processing the longest palindrome string (ii)