Pascal's Triangle code added in Java

PascalsTriangle.java

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+// Pascal's Triangle
+// Problem Description:
+/*
+Given an integer numRows, return the first numRows of Pascal's triangle.
+In Pascal's triangle, each number is the sum of the two numbers directly above it
+*/
+
+// Implementation:
+class Solution {
+    public List<List<Integer>> generate(int numRows) {
+        // Create an array list to store the output result...
+        List<List<Integer>> output = new ArrayList<List<Integer>>();
+        // Base cases...
+	    if (numRows <= 0)  return output;
+        // Create an array list to store the prev triangle value for further addition...
+	    ArrayList<Integer> prev = new ArrayList<Integer>();
+        // Inserting for the first row & store the prev array to the output array...
+	    prev.add(1);
+	    output.add(prev);
+        // For rest of the rows, Traverse all elements through a for loop...
+	    for (int i = 2; i <= numRows; i++) {
+            // Create another array to store the current triangle value...
+		    ArrayList<Integer> curr = new ArrayList<Integer>();
+		    curr.add(1);    //first
+            // Calculate for each of the next values...
+		    for (int j = 0; j < prev.size() - 1; j++) {
+                // Inserting the addition of the prev arry two values...
+			    curr.add(prev.get(j) + prev.get(j + 1));    //middle
+		    }
+            // Store the number 1...
+		    curr.add(1);    //last
+            // Store the value in the Output array...
+		    output.add(curr);
+            // Set prev is equal to curr...
+		    prev = curr;
+	    }
+	    return output;      // Return the output list of pascal values...
+    }
+}