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### leetcode Patching Array

Given a sorted positive integer array nums and an integer n, add/patch elements to the array such that any number in range [1, n] inclusive can be formed by the sum of some elements in the array. Return the minimum number of patches required.

Example 1: nums = [1, 3], n = 6 Return 1.

Combinations of nums are [1], [3], [1,3], which form possible sums of: 1, 3, 4. Now if we add/patch 2 to nums, the combinations are: [1], [2], [3], [1,3], [2,3], [1,2,3]. Possible sums are 1, 2, 3, 4, 5, 6, which now covers the range [1, 6]. So we only need 1 patch.

Example 2: nums = [1, 5, 10], n = 20 Return 2. The two patches can be [2, 4].

Example 3: nums = [1, 2, 2], n = 5 Return 0. 题目地址：leetcode Patching Array

• nums[i] <= known_sum，更新已知范围为：[1,known_sum + nums[i] )
• nums[i] >  known_sum,  添加known_sum进数组才能达到最大的范围，所以已知范围更新为：[1,known_sum *2  )

C++ 8ms

Java 1ms

Python

https://www.hrwhisper.me/leetcode-algorithm-solution/