1539. Kth Missing Positive Number
number
Given an array arr
of positive integers sorted in a strictly increasing order, and an integer k
.
Return the k
th
positive integer that is missing from this array.
Example 1:
Input: arr = [2,3,4,7,11], k = 5
Output: 9
Explanation: The missing positive integers are [1,5,6,8,9,10,12,13,...]. The 5th missing positive integer is 9.
Example 2:
Input: arr = [1,2,3,4], k = 2
Output: 6
Explanation: The missing positive integers are [5,6,7,...]. The 2nd missing positive integer is 6.
Constraints:
1 <= arr.length <= 1000
1 <= arr[i] <= 1000
1 <= k <= 1000
arr[i] < arr[j]
for1 <= i < j <= arr.length
分析
直接遍历数组,一边计算当前缺失了几个数字,一边找。
class Solution:
def findKthPositive(self, arr: List[int], k: int) -> int:
missing = 0
current = 1
i = 0
while True:
if i < len(arr) and arr[i] == current:
i += 1
else:
missing += 1
if missing == k:
return current
current += 1
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