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Jul 5, 2024
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feat: update solutions to lc problem: No.2058 #3205

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127 changes: 53 additions & 74 deletions ....Find the Minimum and Maximum Number of Nodes Between Critical Points/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -95,7 +95,11 @@ tags:

<!-- solution:start -->

### 方法一
### 方法一：直接遍历

根据题目描述，我们需要找出链表的第一个临界点和最后一个临界点位置 $\text{first}$ 和 $\text{last}$，这样可以计算出最大距离 $\text{maxDistance} = \text{last} - \text{first}$。对于最小距离 $\text{minDistance}$，我们需要遍历链表，计算相邻两个临界点之间的距离，取最小值即可。

时间复杂度 $O(n)$，其中 $n$ 是链表的长度。空间复杂度 $O(1)$。

<!-- tabs:start -->

Expand All @@ -109,23 +113,21 @@ tags:
# self.next = next
class Solution:
def nodesBetweenCriticalPoints(self, head: Optional[ListNode]) -> List[int]:
prev, curr = head, head.next
first = last = None
i = 1
ans = [inf, -inf]
while curr.next:
if curr.val < min(prev.val, curr.next.val) or curr.val > max(
prev.val, curr.next.val
):
if last is None:
first = last = -1
i = 0
while head.next.next:
a, b, c = head.val, head.next.val, head.next.next.val
if a > b < c or a < b > c:
if last == -1:
first = last = i
else:
ans[0] = min(ans[0], i - last)
ans[1] = i - first
last = i
ans[1] = max(ans[1], last - first)
i += 1
prev, curr = curr, curr.next
return ans if first != last else [-1, -1]
head = head.next
return [-1, -1] if first == last else ans
```

#### Java
Expand All @@ -142,28 +144,21 @@ class Solution:
* }
*/
class Solution {

public int[] nodesBetweenCriticalPoints(ListNode head) {
ListNode prev = head;
ListNode curr = head.next;
int first = 0, last = 0;
int i = 1;
int[] ans = new int[] {Integer.MAX_VALUE, Integer.MIN_VALUE};
while (curr.next != null) {
if (curr.val < Math.min(prev.val, curr.next.val)
|| curr.val > Math.max(prev.val, curr.next.val)) {
if (last == 0) {
int[] ans = {1 << 30, 0};
int first = -1, last = -1;
for (int i = 0; head.next.next != null; head = head.next, ++i) {
int a = head.val, b = head.next.val, c = head.next.next.val;
if (b < Math.min(a, c) || b > Math.max(a, c)) {
if (last == -1) {
first = i;
last = i;
} else {
ans[0] = Math.min(ans[0], i - last);
ans[1] = i - first;
last = i;
ans[1] = Math.max(ans[1], last - first);
}
}
++i;
prev = curr;
curr = curr.next;
}
return first == last ? new int[] {-1, -1} : ans;
}
Expand All @@ -186,27 +181,22 @@ class Solution {
class Solution {
public:
vector<int> nodesBetweenCriticalPoints(ListNode* head) {
ListNode* prev = head;
ListNode* curr = head->next;
int first = 0, last = 0;
int i = 1;
vector<int> ans(2, INT_MAX);
while (curr->next) {
if (curr->val < min(prev->val, curr->next->val) || curr->val > max(prev->val, curr->next->val)) {
if (last == 0)
vector<int> ans = {1 << 30, 0};
int first = -1, last = -1;
for (int i = 0; head->next->next; head = head->next, ++i) {
int a = head->val, b = head->next->val, c = head->next->next->val;
if (b < min(a, c) || b > max(a, c)) {
if (last == -1) {
first = i;
else {
last = i;
} else {
ans[0] = min(ans[0], i - last);
ans[1] = i - first;
last = i;
ans[1] = max(ans[1], last - first);
}
last = i;
}
++i;
prev = curr;
curr = curr->next;
}
if (first == last) return {-1, -1};
return ans;
return first == last ? vector<int>{-1, -1} : ans;
}
};
```
Expand All @@ -222,22 +212,19 @@ public:
* }
*/
func nodesBetweenCriticalPoints(head *ListNode) []int {
prev, curr := head, head.Next
first, last := 0, 0
i := 1
ans := []int{math.MaxInt32, 0}
for curr.Next != nil {
if curr.Val < min(prev.Val, curr.Next.Val) || curr.Val > max(prev.Val, curr.Next.Val) {
if last == 0 {
ans := []int{1 << 30, 0}
first, last := -1, -1
for i := 0; head.Next.Next != nil; head, i = head.Next, i+1 {
a, b, c := head.Val, head.Next.Val, head.Next.Next.Val
if b < min(a, c) || b > max(a, c) {
if last == -1 {
first, last = i, i
} else {
ans[0] = min(ans[0], i-last)
ans[1] = i - first
last = i
ans[1] = max(ans[1], last-first)
}
}
i++
prev, curr = curr, curr.Next
}
if first == last {
return []int{-1, -1}
Expand All @@ -262,30 +249,22 @@ func nodesBetweenCriticalPoints(head *ListNode) []int {
*/

function nodesBetweenCriticalPoints(head: ListNode | null): number[] {
let idx = 1;
let pre = head.val;
head = head.next;
let nums = [];
while (head.next != null) {
let val = head.val,
post = head.next.val;
if (pre < val && val > post) {
nums.push(idx);
}
if (pre > val && val < post) {
nums.push(idx);
const ans: number[] = [Infinity, 0];
let [first, last] = [-1, -1];
for (let i = 0; head.next.next; head = head.next, ++i) {
const [a, b, c] = [head.val, head.next.val, head.next.next.val];
if (b < Math.min(a, c) || b > Math.max(a, c)) {
if (last < 0) {
first = i;
last = i;
} else {
ans[0] = Math.min(ans[0], i - last);
last = i;
ans[1] = Math.max(ans[1], last - first);
}
}
pre = val;
idx++;
head = head.next;
}
let n = nums.length;
if (n < 2) return [-1, -1];
let min = Infinity;
for (let i = 1; i < n; i++) {
min = Math.min(nums[i] - nums[i - 1], min);
}
return [min, nums[n - 1] - nums[0]];
return first === last ? [-1, -1] : ans;
}
```

Expand Down
127 changes: 53 additions & 74 deletions ...nd the Minimum and Maximum Number of Nodes Between Critical Points/README_EN.md
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Original file line number Diff line number Diff line change
Expand Up @@ -77,7 +77,11 @@ Note that the last node is not considered a local maxima because it does not hav

<!-- solution:start -->

### Solution 1
### Solution 1: Direct Traversal

Based on the problem description, we need to find the positions of the first and last critical points in the linked list, $\text{first}$ and $\text{last}$, respectively. This allows us to calculate the maximum distance $\text{maxDistance} = \text{last} - \text{first}$. For the minimum distance $\text{minDistance}$, we need to traverse the linked list, calculate the distance between two adjacent critical points, and take the minimum value.

The time complexity is $O(n)$, where $n$ is the length of the linked list. The space complexity is $O(1)$.

<!-- tabs:start -->

Expand All @@ -91,23 +95,21 @@ Note that the last node is not considered a local maxima because it does not hav
# self.next = next
class Solution:
def nodesBetweenCriticalPoints(self, head: Optional[ListNode]) -> List[int]:
prev, curr = head, head.next
first = last = None
i = 1
ans = [inf, -inf]
while curr.next:
if curr.val < min(prev.val, curr.next.val) or curr.val > max(
prev.val, curr.next.val
):
if last is None:
first = last = -1
i = 0
while head.next.next:
a, b, c = head.val, head.next.val, head.next.next.val
if a > b < c or a < b > c:
if last == -1:
first = last = i
else:
ans[0] = min(ans[0], i - last)
ans[1] = i - first
last = i
ans[1] = max(ans[1], last - first)
i += 1
prev, curr = curr, curr.next
return ans if first != last else [-1, -1]
head = head.next
return [-1, -1] if first == last else ans
```

#### Java
Expand All @@ -124,28 +126,21 @@ class Solution:
* }
*/
class Solution {

public int[] nodesBetweenCriticalPoints(ListNode head) {
ListNode prev = head;
ListNode curr = head.next;
int first = 0, last = 0;
int i = 1;
int[] ans = new int[] {Integer.MAX_VALUE, Integer.MIN_VALUE};
while (curr.next != null) {
if (curr.val < Math.min(prev.val, curr.next.val)
|| curr.val > Math.max(prev.val, curr.next.val)) {
if (last == 0) {
int[] ans = {1 << 30, 0};
int first = -1, last = -1;
for (int i = 0; head.next.next != null; head = head.next, ++i) {
int a = head.val, b = head.next.val, c = head.next.next.val;
if (b < Math.min(a, c) || b > Math.max(a, c)) {
if (last == -1) {
first = i;
last = i;
} else {
ans[0] = Math.min(ans[0], i - last);
ans[1] = i - first;
last = i;
ans[1] = Math.max(ans[1], last - first);
}
}
++i;
prev = curr;
curr = curr.next;
}
return first == last ? new int[] {-1, -1} : ans;
}
Expand All @@ -168,27 +163,22 @@ class Solution {
class Solution {
public:
vector<int> nodesBetweenCriticalPoints(ListNode* head) {
ListNode* prev = head;
ListNode* curr = head->next;
int first = 0, last = 0;
int i = 1;
vector<int> ans(2, INT_MAX);
while (curr->next) {
if (curr->val < min(prev->val, curr->next->val) || curr->val > max(prev->val, curr->next->val)) {
if (last == 0)
vector<int> ans = {1 << 30, 0};
int first = -1, last = -1;
for (int i = 0; head->next->next; head = head->next, ++i) {
int a = head->val, b = head->next->val, c = head->next->next->val;
if (b < min(a, c) || b > max(a, c)) {
if (last == -1) {
first = i;
else {
last = i;
} else {
ans[0] = min(ans[0], i - last);
ans[1] = i - first;
last = i;
ans[1] = max(ans[1], last - first);
}
last = i;
}
++i;
prev = curr;
curr = curr->next;
}
if (first == last) return {-1, -1};
return ans;
return first == last ? vector<int>{-1, -1} : ans;
}
};
```
Expand All @@ -204,22 +194,19 @@ public:
* }
*/
func nodesBetweenCriticalPoints(head *ListNode) []int {
prev, curr := head, head.Next
first, last := 0, 0
i := 1
ans := []int{math.MaxInt32, 0}
for curr.Next != nil {
if curr.Val < min(prev.Val, curr.Next.Val) || curr.Val > max(prev.Val, curr.Next.Val) {
if last == 0 {
ans := []int{1 << 30, 0}
first, last := -1, -1
for i := 0; head.Next.Next != nil; head, i = head.Next, i+1 {
a, b, c := head.Val, head.Next.Val, head.Next.Next.Val
if b < min(a, c) || b > max(a, c) {
if last == -1 {
first, last = i, i
} else {
ans[0] = min(ans[0], i-last)
ans[1] = i - first
last = i
ans[1] = max(ans[1], last-first)
}
}
i++
prev, curr = curr, curr.Next
}
if first == last {
return []int{-1, -1}
Expand All @@ -244,30 +231,22 @@ func nodesBetweenCriticalPoints(head *ListNode) []int {
*/

function nodesBetweenCriticalPoints(head: ListNode | null): number[] {
let idx = 1;
let pre = head.val;
head = head.next;
let nums = [];
while (head.next != null) {
let val = head.val,
post = head.next.val;
if (pre < val && val > post) {
nums.push(idx);
}
if (pre > val && val < post) {
nums.push(idx);
const ans: number[] = [Infinity, 0];
let [first, last] = [-1, -1];
for (let i = 0; head.next.next; head = head.next, ++i) {
const [a, b, c] = [head.val, head.next.val, head.next.next.val];
if (b < Math.min(a, c) || b > Math.max(a, c)) {
if (last < 0) {
first = i;
last = i;
} else {
ans[0] = Math.min(ans[0], i - last);
last = i;
ans[1] = Math.max(ans[1], last - first);
}
}
pre = val;
idx++;
head = head.next;
}
let n = nums.length;
if (n < 2) return [-1, -1];
let min = Infinity;
for (let i = 1; i < n; i++) {
min = Math.min(nums[i] - nums[i - 1], min);
}
return [min, nums[n - 1] - nums[0]];
return first === last ? [-1, -1] : ans;
}
```

Expand Down
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