Function to push all numbers in each row to the left indiviudually

I have made a function called proc_num which pushes all the numbers in a grid to the left and adds two numbers if they are equal just like the original 2048 game. If a change has been made it returns true otherwise it returns false.

The issue is. In 2048 the numbers are in a grid and each row in the grid needs to be pushed to the left individually. Hence I introduced two limits ei and bi which allows us to only push a range of values to be able to left push each row individually.

Now proc_num works great I tested it. However my proc_num_all which is meant to change the range values to change which row we are pushing outputs 0000... everytime. I went through the debugging process as I was taught but in all honesty I cant find what it is that is failing this programme.

I have tried everything within my means and I cannot figure out what is wrong.

#include <iostream>
#include <cmath>
#include <vector>
#include <fstream>
#include <cstdlib>
#include <ctime>
#include <string>



bool proc_num(std::vector<int>& v, int bi, int ei);
bool proc_num_all(std::vector<int>&v);

int main(){

std::vector<int> v{1,0,1,0,1,0,1,0,1} ;

bool c = proc_num_all(v);

if( c ){
    std::cout << "true" << std::endl;
}

if(!c){
    std::cout << "false" << std::endl;

}

for( int i =0; i<v.size(); i++){
    std::cout <<v[i];
}

return 0;
}


bool proc_num(std::vector<int>& v, int bi, int ei){

std::vector<int> tmp;
std::vector<int> tmp2;
int counter = 0;

// takes out the zeros
for(int i = bi; i< ei ; i++){
    if(v[i]!= 0){
        tmp.push_back(v[i]);
        counter++;
    }
}

// returns false if all equal to zero
if( counter == 0){
    return false;
}

// takes out values for later testing
for( int i = 0; i<v.size(); i++){
    tmp2.push_back(v[i]);
}

// adds if equal
for(int i = 0; i < (tmp.size() - 1); i++){
  if (tmp[i] == tmp[i+1] && tmp.size() != 0){
    tmp[i] = tmp[i]+tmp[i];
    tmp.erase( tmp.begin() + (i+1));
  }
}

int x = 0;
//prints values back in
for( int i = bi; i< tmp.size(); i++){
    v[i] = tmp[x];
    x++;
}
// adds the zeros at the end
for( int i = x; i<ei; i++){
    v[i] = 0;
}
//checks if there has been a change
    if(v==tmp2){
        return false;
    }
return true;
}

bool proc_num(std::vector<int>&v){

int length = std::sqrt(v.size());
bool check = false;

for( int i = 0; i < length; i++){

    int bi = i*length  ;
    int ei = bi +length ;

    if(proc_num(v, bi, ei)){
        check = true;
    }
}
return check;

}