# SPOJ: LPS – Longest Palindromic Substring

0

Solution Idea:
——————
This one is the straight forward implementation of manachar’s algorithm. You can learn about manachar algorithm form the following links-
1. Hackerearth’s Note
2. Hackerank Topic

```
#include &lt;bits/stdc++.h&gt;

#define pii              pair &lt;int,int&gt;
#define pll              pair &lt;long long,long long&gt;
#define sc               scanf
#define pf               printf
#define Pi               2*acos(0.0)
#define ms(a,b)          memset(a, b, sizeof(a))
#define pb(a)            push_back(a)
#define MP               make_pair
#define db               double
#define ll               long long
#define EPS              10E-10
#define ff               first
#define ss               second
#define sqr(x)           (x)*(x)
#define D(x)             cout&lt;&lt;#x &quot; = &quot;&lt;&lt;(x)&lt;&lt;endl
#define VI               vector &lt;int&gt;
#define DBG              pf(&quot;Hi\n&quot;)
#define MOD              1000000007
#define CIN              ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define SZ(a)            (int)a.size()
#define sf(a)            scanf(&quot;%d&quot;,&amp;a)
#define sfl(a)           scanf(&quot;%lld&quot;,&amp;a)
#define sff(a,b)         scanf(&quot;%d %d&quot;,&amp;a,&amp;b)
#define sffl(a,b)        scanf(&quot;%lld %lld&quot;,&amp;a,&amp;b)
#define sfff(a,b,c)      scanf(&quot;%d %d %d&quot;,&amp;a,&amp;b,&amp;c)
#define sfffl(a,b,c)     scanf(&quot;%lld %lld %lld&quot;,&amp;a,&amp;b,&amp;c)
#define stlloop(v)       for(__typeof(v.begin()) it=v.begin();it!=v.end();it++)
#define loop(i,n)        for(int i=0;i&lt;n;i++)
#define loop1(i,n)       for(int i=1;i&lt;=n;i++)
#define REP(i,a,b)       for(int i=a;i&lt;b;i++)
#define RREP(i,a,b)      for(int i=a;i&gt;=b;i--)
#define TEST_CASE(t)     for(int z=1;z&lt;=t;z++)
#define PRINT_CASE       printf(&quot;Case %d: &quot;,z)
#define LINE_PRINT_CASE  printf(&quot;Case %d:\n&quot;,z)
#define CASE_PRINT       cout&lt;&lt;&quot;Case &quot;&lt;&lt;z&lt;&lt;&quot;: &quot;
#define all(a)           a.begin(),a.end()
#define intlim           2147483648
#define infinity         (1&lt;&lt;28)
#define ull              unsigned long long
#define gcd(a, b)        __gcd(a, b)
#define lcm(a, b)        ((a)*((b)/gcd(a,b)))

using namespace std;

/*----------------------Graph Moves----------------*/
//const int fx[]={+1,-1,+0,+0};
//const int fy[]={+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
/*------------------------------------------------*/

//int Set(int N,int pos){return N=N | (1&lt;&lt;pos);}
//int reset(int N,int pos){return N= N &amp; ~(1&lt;&lt;pos);}
//bool check(int N,int pos){return (bool)(N &amp; (1&lt;&lt;pos));}
/*------------------------------------------------*/

#define mx 600005

char s1[mx];
int p[mx];
int n;

string process(string &amp;str)
{
string ret;
ret+='\$';
ret+='#';
for(int i=0;i&lt;SZ(str);i++)
{
ret+=str[i];
ret+='#';
}
ret+='@';
return ret;
//    cout&lt;&lt;str&lt;&lt;endl;
}

int manacher(string &amp;str)
{
int c=0,r=0;
for(int i=1;i&lt;SZ(str)-1;i++)
{
int miror=c+c-i;
if(i&lt;r)
p[i]=min(p[miror],r-i);
while(str[i+1+p[i]]==str[i-1-p[i]])
p[i]++;
if(i+p[i]&gt;r)
{
c=i;
r=i+p[i];
}
}
int ret=0;
for(int i=0;i&lt;SZ(str);i++)
ret=max(ret,p[i]);
return ret;
}

int main()
{

//    freopen(&quot;in.txt&quot;,&quot;r&quot;,stdin);
//	  freopen(&quot;out.txt&quot;,&quot;w&quot;,stdout);

string str;

scanf(&quot;%d&quot;,&amp;n);
scanf(&quot;%s&quot;,s1);

str=s1;
str=process(str);
int ans=manacher(str);
printf(&quot;%d\n&quot;,ans);

return 0;
}

```

# Light OJ: 1255 – Substring Frequency(Hash)

0

```
#include &lt;bits/stdc++.h&gt;

#define pii              pair &lt;int,int&gt;
#define pll              pair &lt;long long,long long&gt;
#define sc               scanf
#define pf               printf
#define Pi               2*acos(0.0)
#define ms(a,b)          memset(a, b, sizeof(a))
#define pb(a)            push_back(a)
#define MP               make_pair
#define db               double
#define ll               long long
#define EPS              10E-10
#define ff               first
#define ss               second
#define sqr(x)           (x)*(x)
#define D(x)             cout&lt;&lt;#x &quot; = &quot;&lt;&lt;(x)&lt;&lt;endl
#define VI               vector &lt;int&gt;
#define DBG              pf(&quot;Hi\n&quot;)
#define MOD              1000000007
#define CIN              ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define SZ(a)            (int)a.size()
#define sf(a)            scanf(&quot;%d&quot;,&amp;a)
#define sfl(a)           scanf(&quot;%lld&quot;,&amp;a)
#define sff(a,b)         scanf(&quot;%d %d&quot;,&amp;a,&amp;b)
#define sffl(a,b)        scanf(&quot;%lld %lld&quot;,&amp;a,&amp;b)
#define sfff(a,b,c)      scanf(&quot;%d %d %d&quot;,&amp;a,&amp;b,&amp;c)
#define sfffl(a,b,c)     scanf(&quot;%lld %lld %lld&quot;,&amp;a,&amp;b,&amp;c)
#define stlloop(v)       for(__typeof(v.begin()) it=v.begin();it!=v.end();it++)
#define loop(i,n)        for(int i=0;i&lt;n;i++)
#define loop1(i,n)       for(int i=1;i&lt;=n;i++)
#define REP(i,a,b)       for(int i=a;i&lt;b;i++)
#define RREP(i,a,b)      for(int i=a;i&gt;=b;i--)
#define TEST_CASE(t)     for(int z=1;z&lt;=t;z++)
#define PRINT_CASE       printf(&quot;Case %d: &quot;,z)
#define CASE_PRINT       cout&lt;&lt;&quot;Case &quot;&lt;&lt;z&lt;&lt;&quot;: &quot;
#define all(a)           a.begin(),a.end()
#define intlim           2147483648
#define infinity         (1&lt;&lt;28)
#define ull              unsigned long long
#define gcd(a, b)        __gcd(a, b)
#define lcm(a, b)        ((a)*((b)/gcd(a,b)))

using namespace std;

/*----------------------Graph Moves----------------*/
//const int fx[]={+1,-1,+0,+0};
//const int fy[]={+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
/*------------------------------------------------*/

//int Set(int N,int pos){return N=N | (1&lt;&lt;pos);}
//int reset(int N,int pos){return N= N &amp; ~(1&lt;&lt;pos);}
//bool check(int N,int pos){return (bool)(N &amp; (1&lt;&lt;pos));}
/*------------------------------------------------*/

/*---------------------Hashing---------------------*/

#define MH 1000006

#define Base1 10000019
#define Base2 10000079

#define MOD1 1000000007
#define MOD2 1000000009

ll B1[MH],B2[MH];

void init_hash()
{
B1[0]=B2[0]=1;
for(int i=1;i&lt;MH;i++)
{
B1[i]=(B1[i-1]*Base1)%MOD1;
B2[i]=(B2[i-1]*Base2)%MOD2;
}
}

struct Hash
{
pll H[MH];
int digit[MH];
int len;

Hash()
{
len=0;
H[0]=pll(0,0);
}

void clear()
{
len=0;
H[0]=pll(0,0);
}

void insert(char ch)
{
len++;
digit[len]=ch-'a'+1;
H[len].ff=(((H[len-1].ff*Base1)%MOD1)+digit[len])%MOD1;
H[len].ss=(((H[len-1].ss*Base2)%MOD2)+digit[len])%MOD2;
}

pll substr(int l, int r)
{
int sub_len=r-l+1;
pll ans;
ans.ff=(H[r].ff-((H[l-1].ff*B1[sub_len])%MOD1)+MOD1)%MOD1;
ans.ss=(H[r].ss-((H[l-1].ss*B2[sub_len])%MOD2)+MOD2)%MOD2;
return ans;
}

pll concate(pll h, int l, int r)
{
pll x=substr(l,r);
int sub_len=r-l+1;
h.ff=(((h.ff*B1[sub_len])%MOD1)+x.ff)%MOD1;
h.ss=(((h.ss*B2[sub_len])%MOD2)+x.ss)%MOD2;
return h;
}

bool operator==(const Hash&amp; p) const
{
return len==p.len &amp;&amp; H[len]==p.H[len];
}

pll &amp; operator[](int index)
{
return H[index];
}
};

Hash h1,h2;

int lcp(int id1, int id2, int l)
{
int lo=1,hi=l;
while(lo&lt;=hi)
{
int mid=(lo+hi)/2;
if(h1.substr(id1,id1+mid)==h2.substr(id2,id2+mid))
lo=mid+1;
else
hi=mid-1;
}
return hi;
}

/*------------------Hashing End---------- ----------*/

char text[MH],pattern[MH];

int main()
{

///freopen(&quot;in.txt&quot;,&quot;r&quot;,stdin);
///freopen(&quot;out.txt&quot;,&quot;w&quot;,stdout);

init_hash();
int t;
sf(t);
getchar();

TEST_CASE(t)
{
sc(&quot;%s %s&quot;,text,pattern);
int l1=strlen(text);
int l2=strlen(pattern);

h1.clear();
h2.clear();

for(int i=0;i&lt;l1;i++)
h1.insert(text[i]);
for(int i=0;i&lt;l2;i++)
h2.insert(pattern[i]);
int ans=0;

for(int i=0;i&lt;=l1-l2;i++)
{
if(h1.substr(i+1,i+l2)==h2[l2])
ans++;
}

PRINT_CASE;
pf(&quot;%d\n&quot;,ans);

}

return 0;
}

```

# UVa 11734 – Big Number of Teams will Solve This

0

```
/*
+-+ +-+ +-+
|R| |.| |S|
+-+ +-+ +-+
*/

#include &lt;bits/stdc++.h&gt;

#define pii             pair &lt;int,int&gt;
#define sc              scanf
#define pf              printf
#define Pi              2*acos(0.0)
#define ms(a,b)         memset(a, b, sizeof(a))
#define pb(a)           push_back(a)
#define MP              make_pair
#define db              double
#define ll              long long
#define EPS             10E-10
#define ff              first
#define ss              second
#define sqr(x)          (x)*(x)
#define D(x)            cout&lt;&lt;#x &quot; = &quot;&lt;&lt;(x)&lt;&lt;endl
#define VI              vector &lt;int&gt;
#define DBG             pf(&quot;Hi\n&quot;)
#define MOD             100007
#define MAX             10000
#define CIN             ios_base::sync_with_stdio(0); cin.tie(0)
#define SZ(a)           (int)a.size()
#define sf(a)           scanf(&quot;%d&quot;,&amp;a)
#define sfl(a)          scanf(&quot;%lld&quot;,&amp;a)
#define sff(a,b)        scanf(&quot;%d %d&quot;,&amp;a,&amp;b)
#define sffl(a,b)       scanf(&quot;%lld %lld&quot;,&amp;a,&amp;b)
#define sfff(a,b,c)     scanf(&quot;%d %d %d&quot;,&amp;a,&amp;b,&amp;c)
#define sfffl(a,b,c)    scanf(&quot;%lld %lld %lld&quot;,&amp;a,&amp;b,&amp;c)
#define loop(i,n)       for(int i=0;i&lt;n;i++)
#define REP(i,a,b)      for(int i=a;i&lt;b;i++)
#define TEST_CASE(t)    for(int z=1;z&lt;=t;z++)
#define PRINT_CASE      printf(&quot;Case %d: &quot;,z)
#define CASE_PRINT      cout&lt;&lt;&quot;Case &quot;&lt;&lt;z&lt;&lt;&quot;: &quot;
#define all(a)          a.begin(),a.end()
#define intlim          2147483648
#define inf             1000000
#define ull             unsigned long long

using namespace std;

/*----------------------Graph Moves----------------*/
//const int fx[]={+1,-1,+0,+0};
//const int fy[]={+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
/*------------------------------------------------*/

//int Set(int N,int pos){return N=N | (1&lt;&lt;pos);}
//int reset(int N,int pos){return N= N &amp; ~(1&lt;&lt;pos);}
//bool check(int N,int pos){return (bool)(N &amp; (1&lt;&lt;pos));}
/*------------------------------------------------*/

int main()
{
///freopen(&quot;in.txt&quot;,&quot;r&quot;,stdin);
///freopen(&quot;out.txt&quot;,&quot;w&quot;,stdout);
int t;
cin&gt;&gt;t;
getchar();
TEST_CASE(t)
{
string s1,s2;
getline(cin,s1);
getline(cin,s2);

CASE_PRINT;

if(s1==s2)
{
cout&lt;&lt;&quot;Yes&quot;&lt;&lt;endl;
}
else
{
string s3;
loop(i,SZ(s1))
{
if(s1[i]!=' ')
s3+=s1[i];
}
if(s3==s2)
cout&lt;&lt;&quot;Output Format Error&quot;&lt;&lt;endl;
else
}

}
return 0;
}

```

# UVa 11734 – Big Number of Teams will Solve This

0
```
/*
User ID: turing_13
*/

#include &lt;bits/stdc++.h&gt;

#define ll long long
#define sc scanf
#define pf printf
#define Pi 2*acos(0.0)

using namespace std;

int main()
{
///freopen(&quot;input.txt&quot;,&quot;r&quot;,stdin);
///freopen(&quot;output.txt&quot;,&quot;w&quot;,stdout);

long long t;
cin&gt;&gt;t;
getchar();
for(int i=1;i&lt;=t;i++)
{
char str1[1000],str2[1000],str3[1000];
gets(str1);
gets(str2);
if(!(strcmp(str1,str2)))
{
cout&lt;&lt;&quot;Case &quot;&lt;&lt;i&lt;&lt;&quot;: Yes&quot;&lt;&lt;endl;
continue;
}
int l=strlen(str1),k=0;
for(int j=0;j&lt;l;j++)
{
if(str1[j]!=' ')
{
str3[k]=str1[j];
k++;
}
}
str3[k]='&#092;&#048;';

if(!(strcmp(str2,str3)))
cout&lt;&lt;&quot;Case &quot;&lt;&lt;i&lt;&lt;&quot;: Output Format Error&quot;&lt;&lt;endl;
else