# 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:
Input: nums = [1,3], n = 6
Output: 1
Explanation:
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:
Input: nums = [1,5,10], n = 20
Output: 2
Explanation: The two patches can be [2, 4].
Example 3:
Input: nums = [1,2,2], n = 5
Output: 0
# Solution
Approach 1: Greedy.
# Code (Python)
Approach 1:
# Code (C++)
Approach 1:
class Solution {
public:
int minPatches(vector<int>& nums, int n) {
int count = 0;
long max = 0;
int i = 0;
while (max < n)
{
if (i == nums.size() || max + 1 < nums[i])
{
count++;
max += max + 1;
}
else
{
max += nums[i];
i++;
}
}
return count;
}
};