My solution to the problem https://www.hackerrank.com/challenges/stockprediction

stock_predictions.cpp

#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <cstdio>
#include <vector>
#include <cstdlib>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
using namespace std;

bool printYO = false;

#define NUM_ITR 4000
#define NORMALISATION 10000.0f
double nextPred(vector<double> curval)
{
    double alpha = 0.001d;
    vector< vector<double> > X;
    vector<double> Y;
    for(int i=0;i<2;++i)
    {
        vector<double> tv;
        tv.push_back(1.0);
        for(int j=0;j<3;++j)
        {
            tv.push_back(curval[i+j]/NORMALISATION);
            tv.push_back(pow(curval[i+j], 0.05)/NORMALISATION);
        }
        Y.push_back(curval[i+3]);
        X.push_back(tv);
    }
    //system("PAUSE");
    vector<double> theta;
    for(int i=0; i<7; ++i)
    {
        theta.push_back(((double)(rand()%100))/100.0d);
    }
    vector<double> delta(7), tdelta(2);
    double s;
    for(int i=0; i<NUM_ITR; ++i)
    {
        /*
            Temp = X*Theta-Y;
            Temp2 = X'*Temp;
            Temp = Theta - alpha*Temp2;
            Theta = Temp;
        */
        for(int k=0;k <2;++k)
        {
            s = 0;
            for(int j=0;j<7;++j)
            {
                s += X[k][j]*theta[j];
            }
            tdelta[k] = s - Y[k];

        }
        if(!(i%500) && printYO)
            {
                cout<<"tdelta is : "<<tdelta[0]<<"  "<<tdelta[1]<<endl;
            }
        for(int j=0; j<7;++j)
        {
            delta[j] = X[0][j] * tdelta[0] + X[1][j] * tdelta[1];
            theta[j] = theta[j] - alpha*delta[j];
        }/*
        if(!(i%500))
        {
            cout<<"Theta after :"<<i<<"Iterations :\n";
            for(int i=0;i<7;++i)
                cout<<theta[i]<<"  ";
            cout<<endl;
        }*/
    }
    vector<double> FS;
    FS.push_back(1);
    for(int j=0;j<3;++j)
    {
        FS.push_back(curval[2+j]/NORMALISATION);
        FS.push_back(pow(curval[2+j], 0.05)/NORMALISATION);
    }
    s = 0;
    for(int i=0;i<7;++i)
    {
        s += FS[i] * theta[i];
    }
    return s;
}

struct profVal
{
    double prof;
    int index;

    profVal(double p, double i) : prof(p), index(i) {}

    bool operator < (const profVal& oth) const
    {
        return (prof < oth.prof);
    }
};

void printTransactions(double m, int k, int d, vector <string> name, vector <int> owned, vector < vector <double> > prices) {
    //Enter your code here
    vector<profVal> profVals;
    double pricenext, prof, curmaxprof = 0;
    int profi = 0;
    vector<string> alltransactions;
    for(int i=0;i<k;++i)
    {/*
        if(i==1)
            printYO = true;*/
        pricenext = nextPred(prices[i]);
        if(pricenext<prices[i][4] && owned[i])
        {
            stringstream temp;
            temp << name[i];
            temp << " SELL ";
            temp << owned[i];
            alltransactions.push_back(temp.str());
        }
        //cout<<"next price "<<i<<" : "<<pricenext<<endl;
        prof = (pricenext - prices[i][4])/prices[i][4];
        profVals.push_back(profVal(prof, i));
        if(prof>curmaxprof)
        {
            curmaxprof = prof;
            profi = i;
        }
    }
    if(curmaxprof>0)
    {
        sort(profVals.begin(), profVals.end());
        int j = k-1, n, t;
        while(profVals[j].prof > 0 && j>=0)
        {
            t = profVals[j].index;
            n = m / prices[t][4];
            if(n>0)
            {
                m -= n*prices[t][4];
                stringstream temp;
                temp << name[t];
                temp << " BUY ";
                temp << n;
                alltransactions.push_back(temp.str());
            }
            --j;
        }
    }
    int sz = alltransactions.size();
    cout<<sz<<endl;
    for(int i=0; i<sz; ++i)
        cout<<alltransactions[i]<<endl;
}

int main(void) {
    //ios_base::sync_with_stdio(false);
    double _m;
    cin >> _m;

    int _k;
    cin >> _k;

    int _d;
    cin >> _d;

    vector<string> _name;
    vector<int> _owned;
    vector < vector <double> > _prices;

    string _name_item;
    char name[100];
    int _owned_item;
    double _prices_item_item;

    for(int _i=0; _i<_k; _i++) {

        cin >> name;
        _name_item = name;
        _name.push_back(_name_item);

        cin >> _owned_item;
        _owned.push_back(_owned_item);

        vector <double> _prices_item;
        for(int _j = 0; _j<5; _j++) {
            cin >> _prices_item_item;
            _prices_item.push_back(_prices_item_item);
        }
        _prices.push_back(_prices_item);
    }

    printTransactions(_m, _k, _d, _name, _owned, _prices);

    return 0;
}