Algorithmic-Coding/String_Hashing at master · sanghaisubham/Algorithmic-Coding · GitHub

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/*Subham Sanghai*/
#include<bits/stdc++.h>
#define mod1 1000000007
#define mod2 1000000009
#define mod3 1000000021
using namespace std;
long long powers(long long a,long long b,long long mod)
{
	if(b==0)
		return 1;
	else if(b%2==0)
	{
		long long s=powers(a,b/2,mod)%mod;
		return (s*s)%mod;
	}
	else
		return (a*powers(a,(b-1),mod))%mod;
}
int   main()
{
	string s;
	cin>>s;
	long long l=s.length();
	long long starthash1[l+1],starthash2[l+1],starthash3[l+1],endhash1[l+1],endhash2[l+1],endhash3[l+1];
	long long val1,val2,val3,start1,start2,start3,end1,end2,end3,length=0;
	starthash1[0]=(s[0]-96);
	string suffix,prefix;
	starthash2[0]=(s[0]-96);
	starthash3[0]=(s[0]-96);
	for(long long i=1;i<l;i++)
	{
		starthash1[i]=((starthash1[i-1]*96)%mod1+(s[i]-96))%mod1;
		starthash2[i]=((starthash2[i-1]*96)%mod2+(s[i]-96))%mod2;
		starthash3[i]=((starthash3[i-1]*96)%mod3+(s[i]-96))%mod3;
	}
	endhash1[l-1]=(s[l-1]-96);
	endhash2[l-1]=(s[l-1]-96);
	endhash3[l-1]=(s[l-1]-96);
	for(long long i=l-2;i>=0;i--)
	{
		endhash1[i]=((endhash1[i+1]*96)%mod1+(s[i]-96))%mod1;
		endhash2[i]=((endhash2[i+1]*96)%mod2+(s[i]-96))%mod2;
		endhash3[i]=((endhash3[i+1]*96)%mod3+(s[i]-96))%mod3;
	}
      //  for(long long i=0;i<l;i++)
       // cout<<starthash1[i]<<" "<<endhash1[i]<<"\n";
	for(long long i=(l/2);i>=0;i--)
	{
			//with odd length
			if((2*i)<l)
			{
			start1=starthash1[i];
			start2=starthash2[i];
			start3=starthash3[i];
			val1=0;
			val2=0;
			val3=0;
			if(((2*i)+1)<l)
			{
			val1=(endhash1[(2*i)+1]*powers(96,(i+1),mod1))%mod1;
			val2=(endhash2[(2*i)+1]*powers(96,(i+1),mod2))%mod2;
			val3=(endhash3[(2*i)+1]*powers(96,(i+1),mod3))%mod3;
			}
			end1=(endhash1[i]-val1+mod1)%mod1;
			end2=(endhash2[i]-val2+mod2)%mod2;
			end3=(endhash3[i]-val3+mod3)%mod3;
			if(start1==end1 && start2==end2 && start3==end3)
			{
				length=(2*i)+1;
			}
			//cout<<i<<" length1 "<<length<<"\n";
			}
			//With even length
			if((2*(i+1))<=l)
			{
				start1=starthash1[i];
			start2=starthash2[i];
			start3=starthash3[i];
			val1=0;
			val2=0;
			val3=0;
			if((2*(i+1))<l)
			{
			val1=(endhash1[(2*(i+1))]*powers(96,(i+1),mod1))%mod1;
			val2=(endhash2[(2*(i+1))]*powers(96,(i+1),mod2))%mod2;
			val3=(endhash3[(2*(i+1))]*powers(96,(i+1),mod3))%mod3;
			}
			end1=(endhash1[i+1]-val1+mod1)%mod1;
			end2=(endhash2[i+1]-val2+mod2)%mod2;
			end3=(endhash3[i+1]-val3+mod3)%mod3;

			if(start1==end1 && start2==end2 && start3==end3)
			{
				length=max(length,(2*(i+1)));
				//cout<<i<<" length2 "<<length<<"\n";
			}
			}
			if(length!=0)
			{
				prefix=s.substr(0,length);
				break;
			}


	}
	length=0;
	string s2;
	s2=s;
	reverse(s2.begin(),s2.end());
	 l=s2.length();
	starthash1[0]=(s2[0]-96);
	starthash2[0]=(s2[0]-96);
	starthash3[0]=(s2[0]-96);
	for(long long i=1;i<l;i++)
	{
		starthash1[i]=((starthash1[i-1]*96)%mod1+(s2[i]-96))%mod1;
		starthash2[i]=((starthash2[i-1]*96)%mod2+(s2[i]-96))%mod2;
		starthash3[i]=((starthash3[i-1]*96)%mod3+(s2[i]-96))%mod3;
	}
	endhash1[l-1]=(s2[l-1]-96);
	endhash2[l-1]=(s2[l-1]-96);
	endhash3[l-1]=(s2[l-1]-96);
	for(long long i=l-2;i>=0;i--)
	{
		endhash1[i]=((endhash1[i+1]*96)%mod1+(s2[i]-96))%mod1;
		endhash2[i]=((endhash2[i+1]*96)%mod2+(s2[i]-96))%mod2;
		endhash3[i]=((endhash3[i+1]*96)%mod3+(s2[i]-96))%mod3;
	}

	for(long long i=(l/2);i>=0;i--)
	{
			//with odd length
			if((2*i)<l)
			{
			start1=starthash1[i];
			start2=starthash2[i];
			start3=starthash3[i];
			val1=0;
			val2=0;
			val3=0;
			if(((2*i)+1)<l)
			{
			val1=(endhash1[(2*i)+1]*powers(96,(i+1),mod1))%mod1;
			val2=(endhash2[(2*i)+1]*powers(96,(i+1),mod2))%mod2;
			val3=(endhash3[(2*i)+1]*powers(96,(i+1),mod3))%mod3;
			}
			end1=(endhash1[i]-val1+mod1)%mod1;
			end2=(endhash2[i]-val2+mod2)%mod2;
			end3=(endhash3[i]-val3+mod3)%mod3;
			if(start1==end1 && start2==end2 && start3==end3)
			{
				length=(2*i)+1;
			}

			}
			//With even length
			if((2*(i+1))<=l)
			{
				start1=starthash1[i];
			start2=starthash2[i];
			start3=starthash3[i];
			val1=0;
			val2=0;
			val3=0;
			if((2*(i+1))<l)
			{
			val1=(endhash1[(2*(i+1))]*powers(96,(i+1),mod1))%mod1;
			val2=(endhash2[(2*(i+1))]*powers(96,(i+1),mod2))%mod2;
			val3=(endhash3[(2*(i+1))]*powers(96,(i+1),mod3))%mod3;
			}
			end1=(endhash1[i+1]-val1+mod1)%mod1;
			end2=(endhash2[i+1]-val2+mod2)%mod2;
			end3=(endhash3[i+1]-val3+mod3)%mod3;

			if(start1==end1 && start2==end2 && start3==end3)
			{
				length=max(length,(2*(i+1)));
			}
			}
			if(length!=0)
			{
				suffix=s2.substr(0,length);
				break;
			}


	}
	string newstring=(suffix+prefix);
	cout<<newstring<<"\n";
string 	A=newstring+'$'+newstring;
	long long l1=newstring.length();

		long long n=A.length();
		long long L = 0, R = 0;
		long long z[n+1];
		fill(z,z+n+1,0);
		for (long long i = 1; i < n; i++)
		{
    		if (i > R)
    		{
        		L = R = i;
       		 while (R < n && A[R-L] == A[R])
        		{
            		R++;
        		}
        		z[i] = R-L;
        		R--;
    		}
    		else
    		{
        		long long k = i-L;
        		if (z[k] < R-i+1)
        		{
            		z[i] = z[k];
        		}
        		else
        		{
            		L = i;
            		while (R < n && A[R-L] == A[R])
            		{
                		R++;
            		}
            		z[i] = R-L;
            		R--;
      		 	 }
    		}
    	}
    	long long count1[l1+2];
    	fill(count1,count1+l1+2,0);
    	for(long long i=l1+1;i<n;i++)
    	{
    	count1[z[i]]++;//if count[6]=1 then it means prefix of length 1,2,3 ... 6 all are present .so  if count1[6]=1 then count of all strings of length 1,2 .. 6 should be increased so we maintained a cum sum
    	}
    	long long sum[l1+2];
    	sum[l1+1]=0;
    	for(long long i=l1;i>=1;i--)
    	{
    	sum[i]=sum[i+1]+count1[i];
    	}
    	for(long long i=1;i<=l1;i++)
    	{
    	cout<<sum[i]<<" ";
    	}
    	cout<<"\n";
    	}