你可不可以
成为我的main函数
做我此生必须有
且只能有一个的入口
——————————
我愿为自己加上private
在你的class中只有
你能调用
——————————————代 码 如 诗 。
Reverse a singly linked list.
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func reverseList(_ head: ListNode?) -> ListNode? { var stack = [Int](), p = head while let t = p { stack.append(t.val) p = t.next } p = head while let t = p { t.val = stack.popLast()! p = t.next } return head } |
You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security system connected and it will automatically contact the police if two adjacent houses were broken into on the same night.
Given a list of non-negative integers representing the amount of money of each house, determine the maximum amount of money you can rob tonight without alerting the police.
Credits:
Special thanks to @ifanchu for adding this problem and creating all test cases. Also thanks to @ts for adding additional test cases.
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func rob(_ nums: [Int]) -> Int { if nums.count < 1 { return nums.first ?? 0 } var lm = 0, gm = 0 for i in 0..<nums.count { let t = lm lm = gm gm = max(gm, t + nums[i]) } return gm } |
Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.
You may assume that the array is non-empty and the majority element always exist in the array.
Credits:
Special thanks to @ts for adding this problem and creating all test cases.
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var v = 0, res = 0 var dict = [Int: Int]() nums.forEach { var t = 1 if let n = dict[$0] { t = n + 1 } if t > v { res = $0 v = t } dict[$0] = t } return res |
Find the contiguous subarray within an array (containing at least one number) which has the largest product.
For example, given the array [2,3,-2,4],
the contiguous subarray [2,3] has the largest product = 6.
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func maxProduct(_ nums: [Int]) -> Int { if nums.isEmpty { return 0 } var gm = nums[0], lmax = nums[0], lmin = nums[0], i = 1 while i < nums.count { let t = [lmax * nums[i], nums[i], lmin * nums[i]] lmin = t.min()! lmax = t.max()! gm = max(lmax, gm) i += 1 } return gm } |
Sort a linked list in O(n log n) time using constant space complexity.
Example 1:
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Input: 4->2->1->3 Output: 1->2->3->4 |
Example 2:
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Input: -1->5->3->4->0 Output: -1->0->3->4->5 |
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func sortList(_ head: ListNode?) -> ListNode? { var arr = Array(repeating: 0, count: 256*128) var i = 0, p = head while let q = p { arr[i] = q.val p = q.next; i += 1 } arr = Array(arr[..<i]).sorted() p = head; i = 0 while let q = p { q.val = arr[i] p = q.next; i += 1 } return head } |
Given an array of integers, every element appears twice except for one. Find that single one.
Note:
Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?
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return nums.reduce(0) { $0 ^ $1 } |