2022-05-29
Suppose an array of length
n sorted in ascending order is rotated between 1 and n times. For example, the array nums = [0,1,2,4,5,6,7] might become:[4,5,6,7,0,1,2]if it was rotated4times.[0,1,2,4,5,6,7]if it was rotated7times.
Notice that rotating an array
[a[0], a[1], a[2], ..., a[n-1]] 1 time results in the array [a[n-1], a[0], a[1], a[2], ..., a[n-2]].Given the sorted rotated array
nums of unique elements, return the minimum element of this array.You must write an algorithm that runs in
O(log n) time.Example 1:
Input: nums = [3,4,5,1,2]
Output: 1
Explanation: The original array was [1,2,3,4,5] rotated 3 times.
Example 2:
Input: nums = [4,5,6,7,0,1,2]
Output: 0
Explanation: The original array was [0,1,2,4,5,6,7] and it was rotated 4 times.
Example 3:
Input: nums = [11,13,15,17]
Output: 11
Explanation: The original array was [11,13,15,17] and it was rotated 4 times.
Constraints:
n == nums.length1 <= n <= 5000-5000 <= nums[i] <= 5000- All the integers of
numsare unique. numsis sorted and rotated between1andntimes.
func findMin(nums []int) int {
n := len(nums)
i, j := 0, n-1
for i < j {
mid := (j-i)/2 + i
if nums[mid] < nums[n-1] {
j = mid
} else {
i = mid + 1
}
}
return nums[i]
}
A peak element is an element that is strictly greater than its neighbors.
Given an integer array
nums, find a peak element, and return its index. If the array contains multiple peaks, return the index to any of the peaks.You may imagine that
nums[-1] = nums[n] = -∞.You must write an algorithm that runs in
O(log n) time.Example 1:
Input: nums = [1,2,3,1]
Output: 2
Explanation: 3 is a peak element and your function should return the index number 2.
Example 2:
Input: nums = [1,2,1,3,5,6,4]
Output: 5
Explanation: Your function can return either index number 1 where the peak element is 2, or index number 5 where the peak element is 6.
Constraints:
1 <= nums.length <= 1000-2^31 <= nums[i] <= 2^31 - 1nums[i] != nums[i + 1]for all validi.
func findPeakElement(nums []int) int {
res := 0
for i, num := range nums {
if num > nums[res] {
res = i
}
}
return res
}
func findPeakElement(nums []int) int {
n := len(nums)
get := func(i int) int {
if i < 0 || i >= n {
return math.MinInt64
}
return nums[i]
}
i, j := 0, n-1
for {
mid := (j-i)/2 + i
if get(mid-1) < get(mid) && get(mid) > get(mid+1) {
return mid
}
if get(mid) < get(mid+1) {
i = mid + 1
} else {
j = mid - 1
}
}
}
Given a string
queryIP, return "IPv4" if IP is a valid IPv4 address, "IPv6" if IP is a valid IPv6 address or "Neither" if IP is not a correct IP of any type.A valid IPv4 address is an IP in the form
"x1.x2.x3.x4" where 0 <= xi <= 255 and xi cannot contain leading zeros. For example, "192.168.1.1" and "192.168.1.0" are valid IPv4 addresses while "192.168.01.1", "192.168.1.00", and "[email protected]" are invalid IPv4 addresses.A valid IPv6 address is an IP in the form
"x1:x2:x3:x4:x5:x6:x7:x8" where:1 <= xi.length <= 4xiis a hexadecimal string which may contain digits, lowercase English letter ('a'to'f') and upper-case English letters ('A'to'F').- Leading zeros are allowed in
xi.
For example, "
2001:0db8:85a3:0000:0000:8a2e:0370:7334" and "2001:db8:85a3:0:0:8A2E:0370:7334" are valid IPv6 addresses, while "2001:0db8:85a3::8A2E:037j:7334" and "02001:0db8:85a3:0000:0000:8a2e:0370:7334" are invalid IPv6 addresses.Example 1:
Input: queryIP = "172.16.254.1"
Output: "IPv4"
Explanation: This is a valid IPv4 address, return "IPv4".
Example 2:
Input: queryIP = "2001:0db8:85a3:0:0:8A2E:0370:7334"
Output: "IPv6"
Explanation: This is a valid IPv6 address, return "IPv6".
Example 3:
Input: queryIP = "256.256.256.256"
Output: "Neither"
Explanation: This is neither a IPv4 address nor a IPv6 address.
Constraints:
queryIPconsists only of English letters, digits and the characters'.'and':'.
func validIPAddress(queryIP string) string {
if parts := strings.Split(queryIP, "."); len(parts) == 4 {
for _, part := range parts {
if len(part) > 1 && part[0] == '0' {
return "Neither"
}
if v, err := strconv.Atoi(part); err != nil || v > 255 {
return "Neither"
}
}
return "IPv4"
}
if parts := strings.Split(queryIP, ":"); len(parts) == 8 {
for _, part := range parts {
if len(part) > 4 {
return "Neither"
}
if _, err := strconv.ParseUint(part, 16, 64); err != nil {
return "Neither"
}
}
return "IPv6"
}
return "Neither"
}
Last modified 9mo ago