Starting linked list

Author: Prashant Jain

src/in/knowledgegate/dsa/linkedlist/PascalTriangle.java

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+package in.knowledgegate.dsa.linkedlist;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * 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 as shown.
+ *
+ * Example 1:
+ * Input: numRows = 5
+ * Output: [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]
+ *
+ * Example 2:
+ * Input: numRows = 1
+ * Output: [[1]]
+ *
+ *
+ * Constraints:
+ * 1 <= numRows <= 30
+ */
+public class PascalTriangle {
+    public List<List<Integer>> generate(int numRows) {
+        List<List<Integer>> result = new ArrayList<>();
+        List<Integer> prev = new ArrayList<>();
+        prev.add(1);
+        result.add(prev);
+
+        for (int i = 1; i < numRows; i++) {
+            List<Integer> curr = new ArrayList<>();
+            curr.add(1);
+            for (int j = 1; j < prev.size(); j++) {
+                curr.add(prev.get(j) + prev.get(j - 1));
+            }
+            curr.add(1);
+            result.add(curr);
+            prev = curr;
+        }
+        return result;
+    }
+}