#CodeChallenge Get the lenght of all the rivers, rivers are represented by 1 and land by 0

RiverSizes.cpp

#include <vector>
using namespace std;

vector<vector<int>> getUnvisitedNeighbors(int i, int j, vector<vector<int>> matrix, vector<vector<int>>& visited) {
	vector<vector<int>> unvisitedNeighbors{};
	// Top
	if (i > 0 && !visited[i - 1][j]) {
		unvisitedNeighbors.push_back({ i - 1, j});
	}
	// Bottom
	if (i < matrix.size() - 1 && !visited[i + 1][j]) {
		unvisitedNeighbors.push_back({ i + 1, j});
	}
	// left
	if (j > 0 && !visited[i][j - 1]) {
		unvisitedNeighbors.push_back({ i, j - 1});
	}
	// Right
	if (j < matrix[0].size() - 1 && !visited[i][j + 1]) {
		unvisitedNeighbors.push_back({ i, j + 1});
	}
	return unvisitedNeighbors;
}

void traverseNode(int i, int j, vector<vector<int>> matrix, vector<vector<int>>* visited, vector<int>* sizes) {
	int currentRiverSize = 0;
	vector<vector<int>> nodesToExplore{{ i, j }}; // * We need pairs to store neighbors
	while (nodesToExplore.size() != 0) { // Depth first search iterative
		vector<int> currentNode = nodesToExplore.back();
		nodesToExplore.pop_back();
		int i = currentNode[0];
		int j = currentNode[1];
		// Method 1, access pointer using dereference. // Acces vector different
		if (((*visited)[i])[j]) { // Skip if visited
			continue;
		}
		visited->at(i)[j] = true; // Mark as visited
		if (matrix[i][j] == 0) { // Skip if land
			continue;
		}
		currentRiverSize += 1; // Then is river, increment.
		// * The format is pairs, so return up to 4 possible pairs.
		vector<vector<int>> unvisitedNeighbors = getUnvisitedNeighbors(i, j, matrix, *visited);
		// Add all the neighbors pairs to nodes to explore queue.
		for (vector<int> neighbor : unvisitedNeighbors) {
			nodesToExplore.push_back(neighbor);
		}
	}
	if (currentRiverSize > 0) {
		sizes->push_back(currentRiverSize);
	}
}

// O(wh) time | O(wh) space
vector<int> riverSizes(vector<vector<int>> matrix) {
  vector<int> sizes = {};
	int height = matrix[0].size();
	vector<vector<int>> visited(matrix.size(), vector<int>(height, false));

	for (int i = 0; i < matrix.size(); i++) {
		for (int j = 0; j < matrix[i].size(); j++) {
			if (visited[i][j]) continue;
			traverseNode(i, j, matrix, &visited, &sizes);
		}
	}
  return sizes;
}