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| import Foundation
class For38Solution {
func findNumsOfK(_ nums: [Int],_ k: Int) -> Int {
var n = nums
let fisrt = getFirstK(&n, k, 0, n.count-1)
let last = getLastK(&n, k, 0, n.count-1)
if fisrt == -1 || last == -1 {
//没找到
return -1
}
return last - fisrt + 1
}
func getFirstK(_ nums: inout [Int],_ k: Int,_ start1: Int,_ end1: Int) -> Int {
var start = start1
var end = end1
if start > end {
return -1
}
let mid = (start + end) / 2
let midNum = nums[mid]
if midNum == k {
if mid == 0 || (mid > 0 && nums[mid - 1] != k) {
return mid
}else {
end = mid - 1
}
}else if midNum > k {
end = mid - 1
}else {
start = mid + 1
}
return getFirstK(&nums, k, start, end)
}
func getLastK(_ nums: inout [Int],_ k: Int,_ start1: Int,_ end1: Int) -> Int {
var start = start1
var end = end1
if start > end {
return -1
}
let mid = (start + end) / 2
let midNum = nums[mid]
if midNum == k {
if mid == end || (mid < end && nums[mid+1] != k) {
return mid
}else {
start = mid + 1
}
}else if midNum < k {
start = mid + 1
}else {
end = mid - 1
}
return getLastK(&nums, k, start, end)
}
}
|
