KMP mode matching 2 (string) and kmp mode matching

KMP mode matching 2 (string) and kmp mode matching
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KMP mode matching 2 (string)
Time Limit:1000 MSMemory Limit:131072KB64bit IO Format:% Lld & % lluSubmit Status

Description

Enter a primary string and a sub-string, and use KMP for matching. If the match fails, the output is 0.

Input

Enter a main string and a sub-string

Output

Number of matched shards

Sample Input

ababcabcacbababcac

Sample Output

3

#include<iostream>#include<cstring>using namespace std;int a[100000];char c[10000];char b[100000];int main(){int j,n,i,k;cin>>c;cin>>b;a[0]=-1;j=-1;i=0;while(b[i]!='\0'){if(j==-1||b[j]==b[i]){j++;i++;//if(b[i]!=b[j])a[i]=j;//else//{if(a[j]==-1)//a[i]=0;//else//a[i]=a[j];}}else j=a[j];}i=0;j=0;k=0;n=1;while(c[i]!='\0'){if(c[i]==b[j]){i++;j++;if(b[j]=='\0'){k=1;break;}}else if(a[j]==-1){i++;j=0;n++;}else {j=a[j];n++;}}if(k==0)cout<<-1<<endl;else cout<<n<<endl;return 0;}

Data Structure string mode matching problem KMP Algorithm

Your program's own ideas are correct, but the errors are as follows:
1. There are strings S and T in the program. You use S [0] to represent the length of the string, but S is a string. Is S [0] A length?
2. in the main function, the S and T you input both use gets (S) or gets (T). Then they all start with 0, and you should process them, make it start with 1 (gets (& S [1]); then S [0] = strlen (& S [1]) + '0 '; when S [0] is used as the length, it can be changed from a character to a number ).

Next [j] of the data structure KMP pattern matching algorithm why is it written below?

Your understanding is a little biased. If you set the pattern string to string [I], calculate next [j], instead of adding one if the first one is equal, it depends on how many substrings are equal, when j = 4, the substring is only string [3] = string [1], so next [j] = 2, similarly, when j = 5, only string [4] = string [1] is available, so next [j] = 2. To use next [5] = 3, you must meet the conditions of string [3] = string [1] and string [4] = string [2.
Do you think the data structure of Tsinghua University is a bit unclear. The algorithm for finding the next array can be viewed several times.