merge sort iterative

#include <bits/stdc++.h>
using namespace std;

#define Gene template< class
#define Rics printer& operator,
Gene c> struct rge{c b, e;};
Gene c> rge<c> range(c i, c j){ return {i, j};}
struct printer{
    ~printer(){cerr<<endl;}
    Gene c >Rics(c x){ cerr<<boolalpha<<x; return *this;}
    Rics(string x){cerr<<x;return *this;}
    Gene c, class d >Rics(pair<c, d> x){ return *this,"(",x.first,", ",x.second,")";}
    Gene ... d, Gene ...> class c >Rics(c<d...> x){ return *this, range(begin(x), end(x));}
    Gene c >Rics(rge<c> x){
        *this,"["; for(auto it = x.b; it != x.e; ++it)
            *this,(it==x.b?"":", "),*it; return *this,"]";}
};
#define debug() cerr<<"LINE "<<__LINE__<<" >> ", printer()
#define dbg(x) "[",#x,": ",(x),"] "
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int my_rand(int l, int r) {
    return uniform_int_distribution<int>(l, r) (rng);
}

// merges v[l...m], v[m+1...r]
void Merge(vector<int> &v, int l, int m, int r) {
    int ptr_l = l, ptr_r = m+1;
    vector<int> merged;
    while(ptr_l <= m or ptr_r <= r) {
        if(ptr_l > m) {
            merged.push_back(v[ptr_r]);
            ptr_r++;
        }
        else if(ptr_r > r or v[ptr_r] > v[ptr_l]) {
            merged.push_back(v[ptr_l]);
            ptr_l++;
        }
        else {
            merged.push_back(v[ptr_r]);
            ptr_r++;
        }
    }
    for(int i = l, j = 0; i <= r; i++, j++) {
        v[i] = merged[j];
    }
}

void Sort(vector<int> &v) {
   int n = v.size();
   for(int cur_size = 1; cur_size < n; cur_size *= 2) {
        for(int left_start = 0; left_start < n; left_start += 2 * cur_size) {
            int mid = min(left_start + cur_size - 1, n - 1);
            if(mid == n-1) continue;
            int right_end = min(left_start + 2 * cur_size - 1, n - 1);
            Merge(v, left_start, mid, right_end);
        }
   }
}

int main() {
//    freopen("in.txt", "r", stdin);
    ios::sync_with_stdio(0);
    cin.tie(0);

    for(int itr = 1; itr <= 10000; itr++) {
        int n = my_rand(1, 100);
        vector<int> v(n);
        for(int i = 0; i < n; i++) {
            v[i] = my_rand(-100000, 100000);
        }
        vector<int> tmp_v = v;
        sort(tmp_v.begin(), tmp_v.end());
        Sort(v);
        assert(v == tmp_v);
    }
}