Added PascalTriangle.java

PascalTriangle.java

@@ -0,0 +1,43 @@
+//Given the num of rows numRows, generate the first numRows of Pascal's Triangle.
+import java.util.ArrayList;
+import java.util.Scanner;
+
+public class PascalTriangle {
+
+    static ArrayList<ArrayList<Integer>> generate(int numRows){
+        ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();
+        if(numRows==0)
+        {
+            return result;
+        }
+
+        ArrayList<Integer> pre = new ArrayList<>();
+        pre.add(1);
+        result.add(pre);
+        for(int i=1;i<=numRows-1;i++)
+        {
+            ArrayList<Integer> cur = new ArrayList<>();
+            cur.add(1); //first
+            for(int j=0;j<pre.size()-1;j++)
+            {
+                cur.add(pre.get(j) + pre.get(j+1)); //middle
+            }
+            cur.add(1); //last
+            result.add(cur);
+            pre=cur;
+        }
+        return result;
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        System.out.println("Program to print the pascal triangle, given the no of rows!!");
+        System.out.print("Enter number of rows: ");
+        int n = sc.nextInt();
+        ArrayList<ArrayList<Integer>> list = generate(n);
+        for(ArrayList<Integer> temp : list)
+        {
+            System.out.println(temp);
+        }
+    }
+}