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June 10, 2021 13:17
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>> Z's Algorithm | |
>>> Resources : | |
1. https://www.youtube.com/watch?v=CpZh4eF8QBw | |
2. https://cp-algorithms.com/string/z-function.html | |
>>> Implementation : | |
void pre(string s,ll *z) | |
{ | |
ll n=s.size(); | |
z[0]=0; | |
ll l=0; | |
ll r=0; | |
for(ll i=1;i<n;i++) | |
{ | |
if(i>r) | |
{ | |
l=i; | |
r=i; | |
while(r<n and s[r]==s[r-l]) | |
{ | |
r++; | |
} | |
z[i]=r-l; | |
r--; | |
} | |
else | |
{ | |
ll k=i-l; | |
if(z[k]+i<=r) | |
{ | |
z[i]=z[k]; | |
} | |
else | |
{ | |
l=i; | |
while(r<n and s[r]==s[r-l]) | |
{ | |
r++; | |
} | |
z[i]=r-l; | |
r--; | |
} | |
} | |
} | |
} | |
ll Z(string s1,string s2) | |
{ | |
string s3=s1+"!"+s2; | |
ll l=s3.size(); | |
ll z[l]; | |
pre(s3,z); | |
ll c=0; | |
for(ll i=0;i<l;i++) | |
{ | |
if(z[i]==s1.size()) | |
{ | |
c++; | |
} | |
} | |
return c; | |
} | |
>>> Problems: | |
Problem-1: http://codeforces.com/problemset/problem/127/D | |
Problem-2: http://codeforces.com/contest/432/problem/D |
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