solves #120 in java

Author: anishLearnsToCode

README.md

@@ -111,7 +111,7 @@
 | 117  | [Populating Next Right Pointers in Each Node II](https://leetcode.com/problems/populating-next-right-pointers-in-each-node-ii)                            |                                                     [![Java](assets/java.png)](src/PopulatingNextRightPointersInEachNodeII.java)                                                     |                                                                                                                                   |
 | 118  | [Pascal's Triangle](https://leetcode.com/problems/pascals-triangle)                                                                                       |                                   [![Java](assets/java.png)](src/PascalsTriangle.java) [![Python](assets/python.png)](python/pascals_triangle.py)                                    |                                                                                                                                   |
 | 119  | [Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii)                                                                                 |                                 [![Java](assets/java.png)](src/PascalsTriangleII.java) [![Python](assets/python.png)](python/pascals_triangle_ii.py)                                 |                                                                                                                                   |
-| 120  | [Triangle](https://leetcode.com/problems/triangle)                                                                                                        |                                                                                                                                                                                      |                                                                                                                                   |
+| 120  | [Triangle](https://leetcode.com/problems/triangle)                                                                                                        |                                                                    [![Java](assets/java.png)](src/Triangle.java)                                                                     |                                                                                                                                   |
 | 121  | [Best Time to Buy and Sell Stocks](https://leetcode.com/problems/best-time-to-buy-and-sell-stock)                                                         |                       [![Java](assets/java.png)](src/BestTimeToBuyAndSellStock.java) [![Python](assets/python.png)](python/best_time_to_buy_and_sell_stock.py)                       |                                                                                                                                   |
 | 122  | [Best Time to Buy and Sell Stocks II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii)                                                   |                    [![Java](assets/java.png)](src/BestTimeToBuyAndSellStockII.java) [![Python](assets/python.png)](python/best_time_to_buy_and_sell_stock_ii.py)                     |                                                                                                                                   |
 | 125  | [Valid Palindrome](https://leetcode.com/problems/valid-palindrome)                                                                                        |                                   [![Java](assets/java.png)](src/ValidPalindrome.java) [![Python](assets/python.png)](python/valid_palindrome.py)                                    |                                                                                                                                   |

src/Triangle.java

@@ -0,0 +1,35 @@
+// https://leetcode.com/problems/triangle
+// T: O(n) where n elements in triangle
+// S: O(1)
+
+import java.util.List;
+
+public class Triangle {
+    public int minimumTotal(List<List<Integer>> triangle) {
+        final int rows = triangle.size();
+        List<Integer> previousRow = triangle.get(0);
+
+        for (int row = 1 ; row < rows ; row++) {
+            final List<Integer> currentRow = triangle.get(row);
+            for (int column = 0 ; column < row + 1 ; column++) {
+                if (column == 0) currentRow.set(column, currentRow.get(column) + previousRow.get(0));
+                else if (column == row) currentRow.set(column, currentRow.get(column) + previousRow.get(row - 1));
+                else currentRow.set(
+                        column,
+                        currentRow.get(column) + Math.min(previousRow.get(column - 1), previousRow.get(column))
+                    );
+            }
+            previousRow = currentRow;
+        }
+
+        return minOfLastRow(triangle);
+    }
+
+    private int minOfLastRow(List<List<Integer>> triangle) {
+        return min(triangle.get(triangle.size() - 1));
+    }
+
+    private int min(List<Integer> array) {
+        return array.stream().min(Integer::compareTo).get();
+    }
+}