Pop Pop watching particles drop.

Expected ouput

 .    
 T .  
  .T .
: : .:

ParticleSim.cpp

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <vector>
#include <string>

using namespace std;

void printV(std::vector<std::vector<int>>&);
void parseIn(std::vector<std::vector<int>>&);
void havokPhysicsTM(std::vector<std::vector<int>>&);
int main()
{
	std::vector<std::vector<int>> v;

	//Read in data
	parseIn(v);
	
	//Input Print
	cout << "Input"<< endl;
	printV(v);
	cout << endl;

	//RUN THE PHYSIX
	havokPhysicsTM(v);

	//Output Print
	cout << "Output" << endl;
	printV(v);

    return 0;
}

void printV(std::vector<std::vector<int>>& data)
{
	int x = data.size();
	int y = data[0].size();
	for (int j = 0; j < y; j++)
	{
		for (int i = 0; i < x; i++)
		{
			switch (data[i][j]) {
			case 0: cout << " ";
				break;
			case 1: cout << ".";
				break;
			case 2: cout << ":";
				break;
			case 3: cout << "T";
				break;
			default: cout << "bro we didn't agree on this character";
				break;
			}

		}
		cout << endl;
	}
}

void parseIn(std::vector<std::vector<int>>& data)
{
	int x, y;
	int j = 0;
	cin >> x >> y;
	data.resize(x, std::vector<int>(y)); //Resize our vector to the STDIN input

	for (string line; getline(cin, line);)
	{
		for (int i = 0; i < line.length(); i++)
		{
			switch (line[i]) {
				case ' ': data[i][j] = 0;
					break;
				case '.': data[i][j] = 1;
					break;
				case ':': data[i][j] = 2;
					break;
				case 'T': data[i][j] = 3;
					break;
				default: cout << "bro we didn't agree on this character";
					break;
			}
			
			if ( (i != 0) && ((i % (x-1)) == 0))
			{
				j++;
			}
		}
	}
}

void havokPhysicsTM(std::vector<std::vector<int>>& data) //Embrace teh jank. Become the jank.
{
	int x = data.size();
	int y = data[0].size();

	for (int i = 0; i < x; i++)
	{
		for (int j = 0; j < y; j++)
		{
			if (data[i][j] == 1)
			{
				if (j < (y-1))
				{
					if (data[i][j + 1] == 0) //we are a . //move down if there's nothing below
					{
						data[i][j + 1] = 1;
						data[i][j] = 0;
					}
					else
						if (data[i][j + 1] == 1) //we are a . //combine if dot below . -> :
						{
							data[i][j + 1] = 2;
							data[i][j] = 0;
						}
						else 
							if ((data[i][j + 1] == 2) && (j + 2 <= y - 1)) //we are a .//below is a : 
							{
								if (data[i][j + 2] == 0) //Not totally sure if this check is nessicary
								{
									data[i][j + 1] = 1;
									data[i][j + 2] = 2;
									data[i][j] = 0;
								}
							}
				}

			}

			if (data[i][j] == 2) //We are a : at start
			{
				if (j < (y - 1))
				{
					if (data[i][j + 1] == 0) //We are a : //There's nothing below
					{
						data[i][j + 1] = 2;
						data[i][j] = 0;
					}
					else
						if (data[i][j + 1] == 1) //We are a : //There's a . below
						{
							if ((j + 2 <= y - 1))
							{
								if (data[i][j + 2] == 0) //We swap places //Can we move both : and . below down? 
								{
									data[i][j + 2] = 2;
									data[i][j + 1] = 1;
									data[i][j] = 0;
								}
							}
							else //Can't move both : and . down so we just swap places.
							{
								data[i][j + 1] = 2;
								data[i][j] = 1;
							}
						}

				}
			}
		}
	}
}

stdin.txt

6 4
.....:
.T    
  .T .
  .