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ngl.go
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ngl.go
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package ngl
import (
"github.com/catorpilor/leetcode/utils"
)
func nextLargeNode(head *utils.ListNode) []int {
return nlg(head)
}
func sdp(head *utils.ListNode) []int {
if head == nil {
return []int{}
}
st := utils.NewStack()
h := head
for h != nil {
st.Push(h.Val)
h = h.Next
}
n := st.Len()
reversd := make([]int, 0, n)
for !st.IsEmpty() {
reversd = append(reversd, st.Pop().(int))
}
res := make([]int, n)
dp := make([]int, n)
dp[0] = -1
for i := 1; i < n; i++ {
if reversd[i] < reversd[i-1] {
dp[i] = i - 1
} else if reversd[i] == reversd[i-1] {
dp[i] = dp[i-1]
} else {
j := dp[i-1]
for j != -1 {
if reversd[j] > reversd[i] {
dp[i] = j
break
}
j = dp[j]
}
if j == -1 && dp[i] == 0 {
dp[i] = j
}
}
}
for i := n - 1; i >= 0; i-- {
if dp[i] != -1 {
res[n-1-i] = reversd[dp[i]]
}
}
return res
}
func nlg(head *utils.ListNode) []int {
if head == nil {
return []int{}
}
var arr []int
for p := head; p != nil; p = p.Next {
arr = append(arr, p.Val)
}
n := len(arr)
res := make([]int, n)
st := utils.NewStack()
for i := 0; i < n; i++ {
for !st.IsEmpty() && arr[st.Top().(int)] < arr[i] {
idx := st.Pop().(int)
res[idx] = arr[i]
}
st.Push(i)
}
return res
}
// useBruteForce time complexity O(N^2), space complexity O(N)
func useBruteForce(head *utils.ListNode) []int {
var res []int
if head == nil {
return res
}
if head.Next == nil {
return []int{0}
}
cur := head
for cur != nil {
right := cur.Next
for right != nil && right.Val <= cur.Val {
right = right.Next
}
if right == nil {
res = append(res, 0)
} else {
res = append(res, right.Val)
}
cur = cur.Next
}
return res
}