Added codes for 18 April

GeeksForGeeks/April/18-4-24/GFG.java

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+//{ Driver Code Starts
+//Initial template for JAVA
+
+import java.util.*;
+import java.lang.*;
+import java.io.*;
+
+class GFG
+ {
+	public static void main (String[] args) throws IOException
+	 {
+	    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	    int t = Integer.parseInt(br.readLine());
+	    for(int i=0;i<t;i++){
+	        int n = Integer.parseInt(br.readLine());
+	        String l = br.readLine();
+    		String[] sarr = l.split(" ");
+    		int[] arr = new int[sarr.length];
+    		for(int i1=0;i1<arr.length;i1++){
+    			arr[i1] = Integer.parseInt(sarr[i1]);
+    		}
+
+            Solution obj = new Solution();
+
+            int[] res = obj.twoRepeated(arr, n);
+            System.out.println(res[0] + " " + res[1]);
+	    }
+	}
+}
+// } Driver Code Ends
+
+
+//User function template for JAVA
+
+class Solution
+{
+    //Function to find two repeated elements.
+    public int[] twoRepeated(int arr[], int n)
+    {
+        // Your code here
+        Set<Integer> set = new HashSet<>();
+
+        int[] ans = new int[2];
+        int j=0;
+        for(int i=0;i<n+2;i++)
+        {
+            if(set.contains(arr[i]) && j!=2)
+            {
+                ans[j]= arr[i];
+                j++;
+
+            }
+
+            else
+            {
+                set.add(arr[i]);
+            }
+        }
+        return ans;
+    }
+
+}

GeeksForGeeks/April/18-4-24/README.md

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+Time complexity - O(n)
+Space complexity - O(1)

LeetCode/April/18-4-24/README.md

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+Time complexity - O(m*n)
+Space complexity - O(1)

LeetCode/April/18-4-24/Solution.java

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+class Solution 
+{
+    public int islandPerimeter(int[][] grid) 
+    {
+        int islands = 0;
+        int neighbors = 0;
+
+        for (int i = 0; i < grid.length; ++i)
+        {
+            for (int j = 0; j < grid[0].length; ++j)
+            {
+                if (grid[i][j] == 1) 
+                {
+                    ++islands;
+                    if (i - 1 >= 0 && grid[i - 1][j] == 1)
+                        ++neighbors;
+                    if (j - 1 >= 0 && grid[i][j - 1] == 1)
+                        ++neighbors;
+                }
+            }
+        }
+
+        return islands * 4 - neighbors * 2;
+    }
+}