Vectors.h

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#pragma once 

#include <vector>

template<typename T>
std::vector<T> slice(const std::vector<T>& v, const size_t start, const int len) {
    std::vector<T> out;
    if(len > 0) { // in case len=-1
        out.resize(len); 
        std::copy(v.begin() + start, v.begin()+start+len, out.begin());
    }
    return out;
}

template<typename T>
std::vector<T> slice(const std::vector<T> &v, const size_t start) {
    // just chop off the end 
    return slice(v, start, v.size()-start);
}

template<typename T>
void increment(std::vector<T>& v, const size_t idx, T count=1) {
    // Increment and potentially increase my vector size if needed
    if(idx >= v.size()) {
        v.resize(idx+1,0);
    }
    
    v[idx] += count;
}

template<typename T>
void glom(std::vector<std::vector<T>*>& X, std::vector<T>*& v) {
    
    // if v is a prefix of anything in x, then 
    // we can just use that. 
    for(auto& x : X) {
        if(is_prefix(*v, *x)) {
            delete v;
            v = x; // set V to the existing datset
            return; 
        }
    }
    
    // else check if v extends anything in X, and if it does, 
    // find the longest match and add the remaining elements
    // to the stuff stored in X
    size_t mx = 0;
    std::vector<T>* match = nullptr;
    for(auto& x : X) {
        if(is_prefix(*x, *v) and x->size() > mx) {
            mx = x->size();
            match = x;
        }
    }   
    
    // if anything matched in X
    if(match != nullptr) {
        
        // append the remaining elements to x
        for(size_t i=mx;i<v->size();i++) 
            match->push_back(v->at(i));
        
        // delete v since its not needed anymore
        delete v;
        
        // and we can use match
        v = match;
    }
    else {
        // else nothing matches so we have to just return v;
        X.push_back(v);
    }
    
    
}