330 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.

详见：https://leetcode.com/problems/patching-array/description/

C++：

class Solution {
public:
    int minPatches(vector<int>& nums, int n) {
        long miss=1,res=0,i=0;
        while(miss<=n)
        {
            if(i<nums.size()&&nums[i]<=miss)
            {
                miss+=nums[i++];
            }
            else
            {
                miss+=miss;
                ++res;
            }
        }
        return res;
    }
};

 参考：https://www.cnblogs.com/grandyang/p/5165821.html