Adding Pascal's Triangle Code

PascalsTriangle.java

@@ -0,0 +1,25 @@
+// TimeComplexity :O(n^2)
+// SpaceComplexity :O(1)
+// Did you get any issue while submitting in LeetCode: No
+// Three lines explanation: Each row starts and ends with 1.
+// Every middle element is the sum of the two elements directly above it from the previous row.
+// All rows are stored in a list and returned at the end.
+
+
+class Solution {
+    public List<List<Integer>> generate(int numRows) {
+        List<List<Integer>> out = new ArrayList<>();
+        for(int i =0; i<numRows; i++) {
+            List<Integer> row = new ArrayList<>();;
+            for(int j=0; j<=i; j++) {
+                if(j==0 || j==i) {
+                    row.add(1);
+                } else {
+                    row.add(out.get(i-1).get(j-1) + out.get(i-1).get(j));
+                }      
+            }  
+            out.add(row);
+        }
+        return out;
+    }
+}