Swapping value

[sarah1993]

Hi everyone. I'm new to C++. I'm seeking for some advise here. I had some problem here. Given matrix (5x15) known as route as below. For each row, I need to select one number randomly and then swap with number next to it. So, the problem is, I need to do this process for 5 generations but the result I obtain for generation 2, 3, 4 and 5 are based on the previous solution.

For example,
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
8 7 6 5 4 3 2 1 15 14 13 12 11 10 9
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
2 4 6 8 10 12 14 15 1 3 5 7 9 11 13
1 3 6 9 12 15 2 4 8 10 14 5 7 13 11

Generation 1
Random no: 4
After swap should be:
1 2 3 5 4 6 7 8 9 10 11 12 13 14 15
8 7 6 5 3 4 2 1 15 14 13 12 11 10 9
15 14 13 12 11 10 9 8 7 6 5 3 4 2 1
2 6 4 8 10 12 14 15 1 3 5 7 9 11 13
1 3 6 9 12 15 2 8 4 10 14 5 7 13 11

Generation 2
Random no: 8
1 2 3 4 5 6 7 9 8 10 11 12 13 14 15
7 8 6 5 4 3 2 1 15 14 13 12 11 10 9
15 14 13 12 11 10 9 7 8 6 5 4 3 2 1
2 4 6 10 8 12 14 15 1 3 5 7 9 11 13
1 3 6 9 12 15 2 4 10 8 14 5 7 13 11

#include <iostream>
#include <vector>
#include <fstream>
#include <sstream>
#include <ctime>
#include <cstdlib>
#include <algorithm>
#include <iterator>

using namespace std;

int main()
{
	// Initialise random seed
	srand(time(NULL));

	vector<vector<int>> route;
	ifstream route_data("route.txt");
	for (string line; getline(route_data, line); )
	{
		route.push_back(vector<int>());
		istringstream iss(line);

		for (int n; iss >> n; )
			route.back().push_back(n);
	}

	int generation = 5;

	for (size_t i = 0; i < generation; i++)
	{
		cout << "Generation: " << i + 1 << "\n";
		cout << "\n";

		int rand_num = rand() % 15;

		cout << "Random number = " << rand_num << "\n";
		cout << "\n";

		for (size_t i = 0; i < route.size(); i++)
		{
			// Iterator to store the position of searched element
			vector<int>::iterator it, ik;

			// Find position of rand_num
			it = find(route[i].begin(), route[i].end(), rand_num);
			if (it != route[i].end())

				ik = it + 1;

			// Swap it and ik
			if (it != route[i].end() && ik != route[i].end())
			{
				iter_swap(it, ik);
			}

			for (size_t j = 0; j < route[i].size(); j++)
			{
				cout << route[i][j] << "    ";
			}
			cout << "\n";
		}
		cout << "\n";
	}
}

[jonnin]

you either have to store each generation, which is wasteful esp if the data gets bigger, or you have to save the swaps and reapply them each time and undo them after, is one way. so if you want gen 4 you would do the first 3 swaps (if original is gen 1?) and that is your gen3 ... do whatever with it .. then undo it back to gen1. Or you can keep gen1 and make ONE copy of gen 1, apply the swaps to get to the desired generation, and copy gen1 back over it when you need a different gen...

ideally you would instead generate each generation, process it and do what needs doing with it, and move to next generation rather than backtrack / redo, but if you can't manage that, one of those ideas...

[memoria]

This is an older post, so I hope you figured it out.

Not sure if I understand the problem here, but I would probably tackle it by storing the random numbers that need to be swapped in a vector. I cannot tell, based on the the way the problem is laid out if you need to base your randomization on numbers that already exist in the matrix.

Then, separately, I would, within a for loop call a couple of functions to check for that number and, if it exists, do the swap. This will make sure that the swaps occur based on previous generations. I'd also pass my vector by reference into these functions, so that it is modified each time. Again, this will ensure that each time I call my functions a new, updated, copy of the vector is passed in.

You've already written some of this, it just needs to be put inside functions.