Added codes for 19 April

GeeksForGeeks/April/19-4-24/GFG.java

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+//{ Driver Code Starts
+//Initial Template for Java
+
+
+
+
+
+import java.io.*;
+import java.util.*;
+
+
+// } Driver Code Ends
+//User function Template for Java
+
+
+
+class Solution
+{
+    ArrayList<Integer> findMissing(int a[], int b[], int n, int m)
+    {
+        Set<Integer> visited = new HashSet<>();
+        for(int val: b) 
+        {
+            visited.add(val);
+        }
+        ArrayList<Integer> result = new ArrayList<>();
+        for(int val: a) 
+        {
+            if(!visited.contains(val)) 
+            {
+                result.add(val);
+            }
+        }
+        return result;
+    }
+}
+
+
+//{ Driver Code Starts.
+
+// Driver class
+class Array {
+
+    // Driver code
+    public static void main(String[] args) throws IOException {
+        // Taking input using buffered reader
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        int testcases = Integer.parseInt(br.readLine());
+        // looping through all testcases
+        while (testcases-- > 0) {
+//            int n = Integer.parseInt(br.readLine());
+            String line = br.readLine();
+            String[] q = line.trim().split("\\s+");
+            int n =Integer.parseInt(q[0]);
+            int m =Integer.parseInt(q[1]);
+            //int y =Integer.parseInt(q[2]);
+            String line1 = br.readLine();
+            String[] a1 = line1.trim().split("\\s+");
+            int a[] = new int[n];
+            for (int i = 0; i < n; i++) {
+                a[i] = Integer.parseInt(a1[i]);
+            }
+            String line2 = br.readLine();
+            String[] a2 = line2.trim().split("\\s+");
+            int b[] = new int[m];
+            for (int i = 0; i < m; i++) {
+                b[i] = Integer.parseInt(a2[i]);
+            }
+            Solution ob = new Solution();
+            ArrayList<Integer> ans=ob.findMissing(a,b,n,m);
+            for (int i = 0; i < ans.size(); i++) {
+                System.out.print(ans.get(i)+" ");
+            }
+            System.out.println();
+
+        }
+    }
+}
+
+
+
+// } Driver Code Ends

GeeksForGeeks/April/19-4-24/README.md

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

LeetCode/April/19-4-24/README.md

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

LeetCode/April/19-4-24/Solution.java

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+class Solution 
+{
+    public int numIslands(char[][] grid) 
+    {
+        int ans = 0;
+
+        for (int i = 0; i < grid.length; ++i)
+            for (int j = 0; j < grid[0].length; ++j)
+                if (grid[i][j] == '1') 
+                {
+                    dfs(grid, i, j);
+                    ++ans;
+                }
+
+        return ans;
+    }
+
+    private void dfs(char[][] grid, int i, int j) 
+    {
+        if (i < 0 || i == grid.length || j < 0 || j == grid[0].length)
+            return;
+        if (grid[i][j] != '1')
+            return;
+
+        grid[i][j] = '2';
+        dfs(grid, i + 1, j);
+        dfs(grid, i - 1, j);
+        dfs(grid, i, j + 1);
+        dfs(grid, i, j - 1);
+    }
+}