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 rotated4
times.[0,1,2,4,5,6,7]
if it was rotated7
times.
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.length
1 <= n <= 5000
-5000 <= nums[i] <= 5000
- All the integers of
nums
are unique. nums
is sorted and rotated between1
andn
times.
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 - 1
nums[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 <= 4
xi
is 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:
queryIP
consists 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 1yr ago