From 80a7a708a67e8063c99513a555bf5e55d98892d2 Mon Sep 17 00:00:00 2001
From: weiy <b754048538@163.com>
Date: Fri, 17 Aug 2018 20:47:44 +0800
Subject: [PATCH] two sum II O(n) easy

---
 Array/TwoSumIIAlreadySorted.py | 42 ++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 Array/TwoSumIIAlreadySorted.py

diff --git a/Array/TwoSumIIAlreadySorted.py b/Array/TwoSumIIAlreadySorted.py
new file mode 100644
index 0000000..0098c2a
--- /dev/null
+++ b/Array/TwoSumIIAlreadySorted.py
@@ -0,0 +1,42 @@
+"""
+Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.
+
+The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2.
+
+Note:
+
+Your returned answers (both index1 and index2) are not zero-based.
+You may assume that each input would have exactly one solution and you may not use the same element twice.
+Example:
+
+Input: numbers = [2,7,11,15], target = 9
+Output: [1,2]
+Explanation: The sum of 2 and 7 is 9. Therefore index1 = 1, index2 = 2.
+
+Two Sum 已经排序后的输出，直接可以O(n):
+
+解释传送门：
+TwoSum.
+ThreeSum.
+
+"""
+class Solution(object):
+    def twoSum(self, sortedNums, target):
+        """
+        :type numbers: List[int]
+        :type target: int
+        :rtype: List[int]
+        """
+        
+        start = 0
+        end = len(sortedNums) - 1
+        while start <= end:
+            # print(nums[start] + nums[end])
+            if sortedNums[start] + sortedNums[end] == target:
+                return start+1, end+1
+            
+            if sortedNums[start] + sortedNums[end] > target:
+                end -= 1
+            else:
+                start += 1
+