solves gas station

Author: anishLearnsToCode

README.md

@@ -120,7 +120,7 @@
 | 130  | [Surrounded Regions](https://leetcode.com/problems/surrounded-regions)                                                                                    |                                                                [![Java](assets/java.png)](src/SurroundedRegions.java)                                                                |                                                                                                                                   |
 | 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)                                                                    |                                                                                                                                   |
-| 134  | [Gas Station](https://leetcode.com/problems/gas-station)                                                                                                  |                                                                                                                                                                                      |                                                                                                                                   |
+| 134  | [Gas Station](https://leetcode.com/problems/gas-station)                                                                                                  |                                                                   [![Java](assets/java.png)](src/GasStation.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)                                                                                        |                                                                                                                                                                                      |                                                                                                                                   |
 | 138  | [Copy List with Random Pointer](https://leetcode.com/problems/copy-list-with-random-pointer)                                                              |                                                                                                                                                                                      |                                                                                                                                   |

src/GasStation.java

@@ -0,0 +1,27 @@
+// https://leetcode.com/problems/gas-station
+// T: O(n)
+// S: O(1)
+
+public class GasStation {
+    public int canCompleteCircuit(int[] gas, int[] cost) {
+        if (sum(gas) < sum(cost)) return -1;
+
+        int startIndex = 0;
+        for (int i = 0, total = 0 ; i < gas.length ; i++) {
+            total += gas[i] - cost[i];
+            if (total < 0) {
+                total = 0;
+                startIndex = i + 1;
+            }
+        }
+        return startIndex;
+    }
+
+    private int sum(int[] array) {
+        int sum = 0;
+        for (int element : array) {
+            sum += element;
+        }
+        return sum;
+    }
+}