day 33: 200-number-of-islands, 141-linked-list-cycle

200-number-of-islands/driver.cpp

@@ -0,0 +1,13 @@
+#include "soln.hpp"
+
+int main()
+{
+	vector<vector<char>> grid{{'1', '1', '1', '1', '0'},
+							  {'1', '1', '0', '1', '0'},
+							  {'1', '1', '1', '0', '1'},
+							  {'0', '0', '0', '1', '1'}};
+	int answer = 2;
+	Solution soln;
+	cout << "Found no. of islands correctly? " << soln.test(grid, answer) << endl;
+	return 0;
+}

200-number-of-islands/soln.cpp

@@ -0,0 +1,52 @@
+#include "soln.hpp"
+
+int Solution::numIslands(vector<vector<char>> &grid)
+{
+	// queue<pair<int,int>> current_island{pair<int,int>{0,0}};
+	int islands = 0;
+	for (int i = 0; i < grid.size(); i++)
+	{
+		for (int j = 0; j < grid[0].size(); j++)
+		{
+			// found land
+			if (grid[i][j] == '1')
+			{
+				islands++;
+				grid[i][j] = '0';
+				queue<pair<int, int>> adjs;
+				adjs.push({i, j});
+				while (!adjs.empty())
+				{
+					pair<int, int> adj = adjs.front();
+					adjs.pop();
+					if (adj.first + 1 < grid.size() && grid[adj.first + 1][adj.second] == '1')
+					{
+						grid[adj.first + 1][adj.second] = '0';
+						adjs.push({adj.first + 1, adj.second});
+					}
+					if (adj.first > 0 && grid[adj.first - 1][adj.second] == '1')
+					{
+						grid[adj.first - 1][adj.second] = '0';
+						adjs.push({adj.first - 1, adj.second});
+					}
+					if (adj.second + 1 < grid[0].size() && grid[adj.first][adj.second + 1] == '1')
+					{
+						grid[adj.first][adj.second + 1] = '0';
+						adjs.push({adj.first, adj.second + 1});
+					}
+					if (adj.second > 0 && grid[adj.first][adj.second - 1] == '1')
+					{
+						grid[adj.first][adj.second - 1] = '0';
+						adjs.push({adj.first, adj.second - 1});
+					}
+				}
+			}
+		}
+	}
+	return islands;
+}
+
+bool Solution::test(vector<vector<char>> &grid, int answer)
+{
+	return numIslands(grid) == answer;
+}

200-number-of-islands/soln.hpp

@@ -0,0 +1,8 @@
+#include <bits/stdc++.h>
+using namespace std;
+class Solution
+{
+public:
+	int numIslands(vector<vector<char>> &grid);
+	bool test(vector<vector<char>> &grid, int answer);
+};