solve problem Gas Station

Author: P-ppc

Diff for: README.md

@@ -297,6 +297,7 @@ All solutions will be accepted!
 |623|[Add One Row To Tree](https://leetcode-cn.com/problems/add-one-row-to-tree/description/)|[java/py/js](./algorithms/AddOneRowToTree)|Medium|
 |513|[Find Bottom Left Tree Value](https://leetcode-cn.com/problems/find-bottom-left-tree-value/description/)|[java/py/js](./algorithms/FindBottomLeftTreeValue)|Medium|
 |103|[Binary Tree Zigzag Level Order Traversal](https://leetcode-cn.com/problems/binary-tree-zigzag-level-order-traversal/description/)|[java/py/js](./algorithms/BinaryTreeZigzagLevelOrderTraversal)|Medium|
+|134|[Gas Station](https://leetcode-cn.com/problems/gas-station/description/)|[java/py/js](./algorithms/GasStation)|Medium|
 
 # Database
 |#|Title|Solution|Difficulty|

Diff for: algorithms/GasStation/README.md

@@ -0,0 +1,2 @@
+# Gas Station
+This problem is easy to solve

Diff for: algorithms/GasStation/Solution.java

@@ -0,0 +1,18 @@
+class Solution {
+    public int canCompleteCircuit(int[] gas, int[] cost) {
+        int total = 0,
+            diffSum = 0,
+            start = 0;
+    
+        for (int i = 0; i < gas.length; i++) {
+            if (diffSum < 0) {
+                diffSum = 0;
+                start = i;
+            }
+            diffSum += gas[i] - cost[i];
+            total += gas[i] - cost[i];
+        }
+
+        return total >= 0 ? start : -1;
+    }
+}

Diff for: algorithms/GasStation/solution.js

@@ -0,0 +1,21 @@
+/**
+ * @param {number[]} gas
+ * @param {number[]} cost
+ * @return {number}
+ */
+var canCompleteCircuit = function(gas, cost) {
+    let total = 0,
+        diffSum = 0,
+        start = 0
+    
+    for (let i = 0; i < gas.length; i++) {
+        if (diffSum < 0) {
+            diffSum = 0
+            start = i
+        }
+        diffSum += gas[i] - cost[i]
+        total += gas[i] - cost[i]
+    }
+    
+    return total >= 0 ? start : -1
+};

Diff for: algorithms/GasStation/solution.py

@@ -0,0 +1,19 @@
+class Solution(object):
+    def canCompleteCircuit(self, gas, cost):
+        """
+        :type gas: List[int]
+        :type cost: List[int]
+        :rtype: int
+        """
+        total = 0
+        diff_sum = 0
+        start = 0
+        
+        for i in xrange(len(gas)):
+            if diff_sum < 0:
+                diff_sum = 0
+                start = i
+            diff_sum += gas[i] - cost[i]
+            total += gas[i] - cost[i]
+            
+        return start if total >= 0 else -1