# [LeetCode] Patching Array 补丁数组

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.

Credits:
Special thanks to @dietpepsi for adding this problem and creating all test cases.

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;
}
};

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

https://leetcode.com/discuss/82895/actually-patching

https://leetcode.com/discuss/82822/solution-explanation

LeetCode All in One 题目讲解汇总(持续更新中...)

posted @ 2016-01-28 12:42  Grandyang  阅读(10089)  评论(11编辑  收藏  举报