Coding Help

BigInt.cpp

struct Bigint {
    string a;
    int sign;
    Bigint(){}
    Bigint(string b){
        *this = b;
    }
    int size(){
        return a.size();
    }
    Bigint inverseSign(){
        sign *= -1;
        return (*this);
    }
    Bigint normalize(int newSign){
        for(int i = a.size() - 1; i > 0 && a[i] == '0'; i--)
            a.erase(a.begin() + i);
        sign = (a.size() == 1 && a[0] == '0') ? 1 : newSign;
        return *this;
    }
    void operator = (string b){
        a = b[0] == '-' ? b.substr(1) : b;
        reverse(a.begin(),a.end());
        this->normalize(b[0] == '-' ? -1 : 1);
    }
    bool operator < ( const Bigint &b ) const{
        if(sign != b.sign) return sign < b.sign;
        if(a.size() != b.a.size())
            return sign == 1 ? a.size() < b.a.size() : a.size() > b.a.size();
        for(int i = a.size() - 1; i >= 0; i--)
        	if(a[i] != b.a[i])
                return sign == 1 ? a[i] < b.a[i] : a[i] > b.a[i];
        return false;
    }
    bool operator == ( const Bigint &b ) const{
        return a == b.a && sign == b.sign;
    }
    Bigint operator + (Bigint b){
        if( sign != b.sign ) return (*this) - b.inverseSign();
        Bigint c;
        for(int i = 0, carry = 0; i<a.size() || i<b.size() || carry; i++ ){
            carry+=(i<a.size() ? a[i]-48 : 0)+(i<b.a.size() ? b.a[i]-48 : 0);
            c.a += (carry % 10 + 48);
            carry /= 10;
        }
        return c.normalize(sign);
    }
    Bigint operator - (Bigint b){
        if(sign != b.sign) return (*this) + b.inverseSign();
        int s = sign;
        sign = b.sign = 1;
        if( (*this) < b ) return ((b - (*this)).inverseSign()).normalize(-s);
        Bigint c;
        for( int i = 0, borrow = 0; i < a.size(); i++ ){
            borrow = a[i] - borrow - (i < b.size() ? b.a[i] : 48);
            c.a += borrow >= 0 ? borrow + 48 : borrow + 58;
            borrow = borrow >= 0 ? 0 : 1;
        }
        return c.normalize(s);
    }
    Bigint operator * (Bigint b){
        Bigint c("0");
        for(int i = 0, k = a[i] - 48; i < a.size(); i++, k = a[i] - 48){
            while(k--) c = c + b;
            b.a.insert(b.a.begin(), '0');
        }
        return c.normalize(sign * b.sign);
    }
    Bigint operator / (Bigint b){
        if(b.size() == 1 && b.a[0] == '0' ) b.a[0] /= ( b.a[0] - 48);
        Bigint c("0"), d;
        for(int j = 0; j < a.size(); j++) d.a += "0";
        int dSign = sign * b.sign;
        b.sign = 1;
        for(int i = a.size() - 1; i >= 0; i--){
            c.a.insert( c.a.begin(), '0');
            c = c + a.substr(i, 1);
            while( !( c < b ) ) c = c - b, d.a[i]++;
        }
        return d.normalize(dSign);
    }
    Bigint operator % (Bigint b){
        if(b.size() == 1 && b.a[0] == '0') b.a[0] /= (b.a[0] - 48);
        Bigint c("0");
        b.sign = 1;
        for(int i = a.size() - 1; i >= 0; i--){
            c.a.insert( c.a.begin(), '0');
            c = c + a.substr(i, 1);
            while( !( c < b ) ) c = c - b;
        }
        return c.normalize(sign);
    }
    void print(){
        if(sign == -1 ) putchar('-');
        for(int i = a.size() - 1; i >= 0; i-- ) putchar(a[i]);
    }
};

BigMod.cpp

long long bigmod(long long n, long long p) {
    if(p == 0) return 1;
    else if(p & 1) return (n * bigmod(n, p - 1)) % mod;
    else{
        long long x = bigmod(n, p / 2);
        return (x * x) % mod;
    }
}

Catalan Number.cpp

/*
  Catalan Series : 1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, .................
  Nth Catalan number, Cat(n) = (2n C n) / (n + 1)
  Recursive relation, Cat(n) = sum ( C(i) * C(n-i) ), where i in [0,n]
  		      Cat(n) = Cat(n-1) * (4n - 2) / (n + 1)
*/

long long cat[N];
void precalc(){
	cat[0] = 1;
	for(int i = 1; i < N; i++){
		cat[i] = 0;
		for(int j = 0; j < i; j++){
			cat[i] = cat[i] +  cat[j] * cat[i-j-1];
		}
	}
}

long long cat[N];
void precalc(){
	cat[0] = 1;
	for(int i = 1; i < N; i++){
		cat[i] = cat[i-1] * (4 * i - 2) / ( i + 1);
	}
}

FastIO.java

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.InputStreamReader;
import java.util.StringTokenizer;
import java.io.BufferedReader;
import java.math.BigInteger;

public class FastIO{
	
	static InputReader in;
	static PrintWriter out;

    static class Task {
        public void solve(InputReader in, PrintWriter out) throws FileNotFoundException {
            
        }
    }
    
    public static void main(String[] args) throws FileNotFoundException{
    	fread();
    	//sysread();
      	Task solver = new Task();
	solver.solve(in, out);
      	out.close();
    }
    
    public static void fread() throws FileNotFoundException {
    	in = new InputReader(new FileInputStream("input.txt"));
    	out = new PrintWriter(new FileOutputStream("output.txt"));
    }
    
    public static void sysread() throws FileNotFoundException {
    	in = new InputReader(System.in);
    	out = new PrintWriter(System.out);
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }
        
        public BigInteger nextBigInteger(){
        	return new BigInteger(next());
        }
    }
}

Mobius.cpp

void Mobius(){
       mu[1] = 1;
       for(int i = 1; i < N; i++){
            if(mu[i]){
                   for(int j = i + i; j < N; j += i){
                        mu[j]  -=  mu[i];
                    }
            }
        }
}

Schroeder Number.cpp

/*
  Schroeder Series : 1, 1, 3, 11, 45, 197, 903, 4279, 20793, 103049, 518859, 2646723, 13648869, 71039373,.............
  Recursive relation, Sch(n) = ( (6n - 3) * Sch(n - 1) - (n - 2) * Sch(n - 2) ) / (n + 1)
*/

long long sch[N];

void precalc(){
	sch[0] = sch[1] = 1;
	for(int i = 2; i < N; i++){
		sch[i] = ((6*i - 3) * sch[i-1] - (i - 2) * sch[i-2]) / (i + 1);
	}
}