solves #135: Candy in java

Author: anishLearnsToCode

Diff for: README.md

@@ -125,6 +125,7 @@
 | 131  | [Palindrome Partitioning](https://leetcode.com/problems/palindrome-partitioning)                                                                                       |                                                                                   [![Java](assets/java.png)](src/PalindromePartitioning.java)                                                                                    |                                                                                                                                   |
 | 133  | [Clone Graph](https://leetcode.com/problems/clone-graph)                                                                                                               |                                                              [![Java](assets/java.png)](src/CloneGraph.java) [![Python](assets/python.png)](python/clone_graph.py)                                                               |                                                                                                                                   |
 | 134  | [Gas Station](https://leetcode.com/problems/gas-station)                                                                                                               |                                                                                         [![Java](assets/java.png)](src/GasStation.java)                                                                                          |                                                                                                                                   |
+| 135  | [Candy](https://leetcode.com/problems/candy)                                                                                                                           |                                                                                            [![Java](assets/java.png)](src/Candy.java)                                                                                            |                                                                                                                                   |
 | 136  | [Single Number](https://leetcode.com/problems/single-number)                                                                                                           |                                                            [![Java](assets/java.png)](src/SingleNumber.java) [![Python](assets/python.png)](python/single_number.py)                                                             |                                                                                                                                   |
 | 137  | [Single Number II](https://leetcode.com/problems/single-number-ii)                                                                                                     |                                                                                       [![Java](assets/java.png)](src/SingleNumberII.java)                                                                                        |                                                                                                                                   |
 | 138  | [Copy List with Random Pointer](https://leetcode.com/problems/copy-list-with-random-pointer)                                                                           |                                                                                  [![Java](assets/java.png)](src/CopyListWithRandomPointer.java)                                                                                  |                                                                                                                                   |

Diff for: src/Candy.java

@@ -0,0 +1,27 @@
+// https://leetcode.com/problems/candy
+// T: O(N)
+// S: O(N)
+
+import java.util.Arrays;
+
+public class Candy {
+    public int candy(int[] ratings) {
+        final int[] candies = new int[ratings.length];
+
+        // left pass
+        for (int i = 1 ; i < ratings.length ; i++) {
+            if (ratings[i] > ratings[i - 1]) {
+                candies[i] = candies[i - 1] + 1;
+            }
+        }
+
+        // right pass
+        for (int i = ratings.length - 2 ; i >= 0 ; i--) {
+            if (ratings[i] > ratings[i + 1]) {
+                candies[i] = Math.max(candies[i], candies[i + 1] + 1);
+            }
+        }
+
+        return Arrays.stream(candies).sum() + ratings.length;
+    }
+}

Diff for: src/HelloWorld.java

@@ -1,39 +1,22 @@
-import java.util.*;
+import java.util.Arrays;
 
 public class HelloWorld {
-    static class RandomizedSet {
-        private final Random random = new Random();
-        private final List<Integer> list = new ArrayList<>();
-        private final Map<Integer, Integer> indexMapping = new HashMap<>();
+    public int canCompleteCircuit(int[] gas, int[] cost) {
+        final int totalGas = Arrays.stream(gas).sum();
+        final int totalCost = Arrays.stream(cost).sum();
 
-        public boolean insert(int val) {
-            if (indexMapping.containsKey(val)) {
-                return false;
-            }
-            list.add(val);
-            indexMapping.put(val, list.size() - 1);
-            return true;
-        }
-
-        private int last() {
-            return this.list.getLast();
+        if (totalCost > totalGas) {
+            return -1;
         }
 
-        public boolean remove(int val) {
-            if (!indexMapping.containsKey(val)) {
-                return false;
+        int startingIndex = 0;
+        for (int i = 0, currentGas = 0 ; i < cost.length ; i++) {
+            currentGas += gas[i] - cost[i];
+            if (currentGas < 0) {
+                currentGas = 0;
+                startingIndex = i + 1;
             }
-            final int index = indexMapping.get(val);
-            indexMapping.put(last(), index);
-            indexMapping.remove(val);
-            list.set(index, last());
-            list.removeLast();
-            return true;
-        }
-
-        public int getRandom() {
-            final int randomIndex = random.nextInt(list.size());
-            return list.get(randomIndex);
         }
+        return startingIndex;
     }
 }