Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly
Sign up
Appearance settings

Commit a491049

Browse files
feat: update solutions to lc problem: No.2058 (doocs#3205)
No.2058.Find the Minimum and Maximum Number of Nodes Between Critical Points
1 parent c37bbd5 commit a491049

File tree

7 files changed

+154
-221
lines changed

7 files changed

+154
-221
lines changed

‎solution/2000-2099/2058.Find the Minimum and Maximum Number of Nodes Between Critical Points/README.md‎

Lines changed: 53 additions & 74 deletions
Original file line numberDiff line numberDiff line change
@@ -95,7 +95,11 @@ tags:
9595

9696
<!-- solution:start -->
9797

98-
### 方法一
98+
### 方法一:直接遍历
99+
100+
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},ドル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},ドル我们需要遍历链表,计算相邻两个临界点之间的距离,取最小值即可。
101+
102+
时间复杂度 $O(n),ドル其中 $n$ 是链表的长度。空间复杂度 $O(1)$。
99103

100104
<!-- tabs:start -->
101105

@@ -109,23 +113,21 @@ tags:
109113
# self.next = next
110114
class Solution:
111115
def nodesBetweenCriticalPoints(self, head: Optional[ListNode]) -> List[int]:
112-
prev, curr = head, head.next
113-
first = last = None
114-
i = 1
115116
ans = [inf, -inf]
116-
while curr.next:
117-
if curr.val < min(prev.val, curr.next.val) or curr.val > max(
118-
prev.val, curr.next.val
119-
):
120-
if last is None:
117+
first = last = -1
118+
i = 0
119+
while head.next.next:
120+
a, b, c = head.val, head.next.val, head.next.next.val
121+
if a > b < c or a < b > c:
122+
if last == -1:
121123
first = last = i
122124
else:
123125
ans[0] = min(ans[0], i - last)
124-
ans[1] = i - first
125126
last = i
127+
ans[1] = max(ans[1], last - first)
126128
i += 1
127-
prev, curr = curr, curr.next
128-
return ans if first != last else [-1, -1]
129+
head = head.next
130+
return [-1, -1] if first == last else ans
129131
```
130132

131133
#### Java
@@ -142,28 +144,21 @@ class Solution:
142144
* }
143145
*/
144146
class Solution {
145-
146147
public int[] nodesBetweenCriticalPoints(ListNode head) {
147-
ListNode prev = head;
148-
ListNode curr = head.next;
149-
int first = 0, last = 0;
150-
int i = 1;
151-
int[] ans = new int[] {Integer.MAX_VALUE, Integer.MIN_VALUE};
152-
while (curr.next != null) {
153-
if (curr.val < Math.min(prev.val, curr.next.val)
154-
|| curr.val > Math.max(prev.val, curr.next.val)) {
155-
if (last == 0) {
148+
int[] ans = {1 << 30, 0};
149+
int first = -1, last = -1;
150+
for (int i = 0; head.next.next != null; head = head.next, ++i) {
151+
int a = head.val, b = head.next.val, c = head.next.next.val;
152+
if (b < Math.min(a, c) || b > Math.max(a, c)) {
153+
if (last == -1) {
156154
first = i;
157155
last = i;
158156
} else {
159157
ans[0] = Math.min(ans[0], i - last);
160-
ans[1] = i - first;
161158
last = i;
159+
ans[1] = Math.max(ans[1], last - first);
162160
}
163161
}
164-
++i;
165-
prev = curr;
166-
curr = curr.next;
167162
}
168163
return first == last ? new int[] {-1, -1} : ans;
169164
}
@@ -186,27 +181,22 @@ class Solution {
186181
class Solution {
187182
public:
188183
vector<int> nodesBetweenCriticalPoints(ListNode* head) {
189-
ListNode* prev = head;
190-
ListNode* curr = head->next;
191-
int first = 0, last = 0;
192-
int i = 1;
193-
vector<int> ans(2, INT_MAX);
194-
while (curr->next) {
195-
if (curr->val < min(prev->val, curr->next->val) || curr->val > max(prev->val, curr->next->val)) {
196-
if (last == 0)
184+
vector<int> ans = {1 << 30, 0};
185+
int first = -1, last = -1;
186+
for (int i = 0; head->next->next; head = head->next, ++i) {
187+
int a = head->val, b = head->next->val, c = head->next->next->val;
188+
if (b < min(a, c) || b > max(a, c)) {
189+
if (last == -1) {
197190
first = i;
198-
else {
191+
last = i;
192+
} else {
199193
ans[0] = min(ans[0], i - last);
200-
ans[1] = i - first;
194+
last = i;
195+
ans[1] = max(ans[1], last - first);
201196
}
202-
last = i;
203197
}
204-
++i;
205-
prev = curr;
206-
curr = curr->next;
207198
}
208-
if (first == last) return {-1, -1};
209-
return ans;
199+
return first == last ? vector<int>{-1, -1} : ans;
210200
}
211201
};
212202
```
@@ -222,22 +212,19 @@ public:
222212
* }
223213
*/
224214
func nodesBetweenCriticalPoints(head *ListNode) []int {
225-
prev, curr := head, head.Next
226-
first, last := 0, 0
227-
i := 1
228-
ans := []int{math.MaxInt32, 0}
229-
for curr.Next != nil {
230-
if curr.Val < min(prev.Val, curr.Next.Val) || curr.Val > max(prev.Val, curr.Next.Val) {
231-
if last == 0 {
215+
ans := []int{1 << 30, 0}
216+
first, last := -1, -1
217+
for i := 0; head.Next.Next != nil; head, i = head.Next, i+1 {
218+
a, b, c := head.Val, head.Next.Val, head.Next.Next.Val
219+
if b < min(a, c) || b > max(a, c) {
220+
if last == -1 {
232221
first, last = i, i
233222
} else {
234223
ans[0] = min(ans[0], i-last)
235-
ans[1] = i - first
236224
last = i
225+
ans[1] = max(ans[1], last-first)
237226
}
238227
}
239-
i++
240-
prev, curr = curr, curr.Next
241228
}
242229
if first == last {
243230
return []int{-1, -1}
@@ -262,30 +249,22 @@ func nodesBetweenCriticalPoints(head *ListNode) []int {
262249
*/
263250

264251
function nodesBetweenCriticalPoints(head: ListNode | null): number[] {
265-
let idx = 1;
266-
let pre = head.val;
267-
head = head.next;
268-
let nums = [];
269-
while (head.next != null) {
270-
let val = head.val,
271-
post = head.next.val;
272-
if (pre < val && val > post) {
273-
nums.push(idx);
274-
}
275-
if (pre > val && val < post) {
276-
nums.push(idx);
252+
const ans: number[] = [Infinity, 0];
253+
let [first, last] = [-1, -1];
254+
for (let i = 0; head.next.next; head = head.next, ++i) {
255+
const [a, b, c] = [head.val, head.next.val, head.next.next.val];
256+
if (b < Math.min(a, c) || b > Math.max(a, c)) {
257+
if (last < 0) {
258+
first = i;
259+
last = i;
260+
} else {
261+
ans[0] = Math.min(ans[0], i - last);
262+
last = i;
263+
ans[1] = Math.max(ans[1], last - first);
264+
}
277265
}
278-
pre = val;
279-
idx++;
280-
head = head.next;
281-
}
282-
let n = nums.length;
283-
if (n < 2) return [-1, -1];
284-
let min = Infinity;
285-
for (let i = 1; i < n; i++) {
286-
min = Math.min(nums[i] - nums[i - 1], min);
287266
}
288-
return [min, nums[n-1] -nums[0]];
267+
return first===last? [-1, -1] :ans;
289268
}
290269
```
291270

‎solution/2000-2099/2058.Find the Minimum and Maximum Number of Nodes Between Critical Points/README_EN.md‎

Lines changed: 53 additions & 74 deletions
Original file line numberDiff line numberDiff line change
@@ -77,7 +77,11 @@ Note that the last node is not considered a local maxima because it does not hav
7777

7878
<!-- solution:start -->
7979

80-
### Solution 1
80+
### Solution 1: Direct Traversal
81+
82+
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},ドル respectively. This allows us to calculate the maximum distance $\text{maxDistance} = \text{last} - \text{first}$. For the minimum distance $\text{minDistance},ドル we need to traverse the linked list, calculate the distance between two adjacent critical points, and take the minimum value.
83+
84+
The time complexity is $O(n),ドル where $n$ is the length of the linked list. The space complexity is $O(1)$.
8185

8286
<!-- tabs:start -->
8387

@@ -91,23 +95,21 @@ Note that the last node is not considered a local maxima because it does not hav
9195
# self.next = next
9296
class Solution:
9397
def nodesBetweenCriticalPoints(self, head: Optional[ListNode]) -> List[int]:
94-
prev, curr = head, head.next
95-
first = last = None
96-
i = 1
9798
ans = [inf, -inf]
98-
while curr.next:
99-
if curr.val < min(prev.val, curr.next.val) or curr.val > max(
100-
prev.val, curr.next.val
101-
):
102-
if last is None:
99+
first = last = -1
100+
i = 0
101+
while head.next.next:
102+
a, b, c = head.val, head.next.val, head.next.next.val
103+
if a > b < c or a < b > c:
104+
if last == -1:
103105
first = last = i
104106
else:
105107
ans[0] = min(ans[0], i - last)
106-
ans[1] = i - first
107108
last = i
109+
ans[1] = max(ans[1], last - first)
108110
i += 1
109-
prev, curr = curr, curr.next
110-
return ans if first != last else [-1, -1]
111+
head = head.next
112+
return [-1, -1] if first == last else ans
111113
```
112114

113115
#### Java
@@ -124,28 +126,21 @@ class Solution:
124126
* }
125127
*/
126128
class Solution {
127-
128129
public int[] nodesBetweenCriticalPoints(ListNode head) {
129-
ListNode prev = head;
130-
ListNode curr = head.next;
131-
int first = 0, last = 0;
132-
int i = 1;
133-
int[] ans = new int[] {Integer.MAX_VALUE, Integer.MIN_VALUE};
134-
while (curr.next != null) {
135-
if (curr.val < Math.min(prev.val, curr.next.val)
136-
|| curr.val > Math.max(prev.val, curr.next.val)) {
137-
if (last == 0) {
130+
int[] ans = {1 << 30, 0};
131+
int first = -1, last = -1;
132+
for (int i = 0; head.next.next != null; head = head.next, ++i) {
133+
int a = head.val, b = head.next.val, c = head.next.next.val;
134+
if (b < Math.min(a, c) || b > Math.max(a, c)) {
135+
if (last == -1) {
138136
first = i;
139137
last = i;
140138
} else {
141139
ans[0] = Math.min(ans[0], i - last);
142-
ans[1] = i - first;
143140
last = i;
141+
ans[1] = Math.max(ans[1], last - first);
144142
}
145143
}
146-
++i;
147-
prev = curr;
148-
curr = curr.next;
149144
}
150145
return first == last ? new int[] {-1, -1} : ans;
151146
}
@@ -168,27 +163,22 @@ class Solution {
168163
class Solution {
169164
public:
170165
vector<int> nodesBetweenCriticalPoints(ListNode* head) {
171-
ListNode* prev = head;
172-
ListNode* curr = head->next;
173-
int first = 0, last = 0;
174-
int i = 1;
175-
vector<int> ans(2, INT_MAX);
176-
while (curr->next) {
177-
if (curr->val < min(prev->val, curr->next->val) || curr->val > max(prev->val, curr->next->val)) {
178-
if (last == 0)
166+
vector<int> ans = {1 << 30, 0};
167+
int first = -1, last = -1;
168+
for (int i = 0; head->next->next; head = head->next, ++i) {
169+
int a = head->val, b = head->next->val, c = head->next->next->val;
170+
if (b < min(a, c) || b > max(a, c)) {
171+
if (last == -1) {
179172
first = i;
180-
else {
173+
last = i;
174+
} else {
181175
ans[0] = min(ans[0], i - last);
182-
ans[1] = i - first;
176+
last = i;
177+
ans[1] = max(ans[1], last - first);
183178
}
184-
last = i;
185179
}
186-
++i;
187-
prev = curr;
188-
curr = curr->next;
189180
}
190-
if (first == last) return {-1, -1};
191-
return ans;
181+
return first == last ? vector<int>{-1, -1} : ans;
192182
}
193183
};
194184
```
@@ -204,22 +194,19 @@ public:
204194
* }
205195
*/
206196
func nodesBetweenCriticalPoints(head *ListNode) []int {
207-
prev, curr := head, head.Next
208-
first, last := 0, 0
209-
i := 1
210-
ans := []int{math.MaxInt32, 0}
211-
for curr.Next != nil {
212-
if curr.Val < min(prev.Val, curr.Next.Val) || curr.Val > max(prev.Val, curr.Next.Val) {
213-
if last == 0 {
197+
ans := []int{1 << 30, 0}
198+
first, last := -1, -1
199+
for i := 0; head.Next.Next != nil; head, i = head.Next, i+1 {
200+
a, b, c := head.Val, head.Next.Val, head.Next.Next.Val
201+
if b < min(a, c) || b > max(a, c) {
202+
if last == -1 {
214203
first, last = i, i
215204
} else {
216205
ans[0] = min(ans[0], i-last)
217-
ans[1] = i - first
218206
last = i
207+
ans[1] = max(ans[1], last-first)
219208
}
220209
}
221-
i++
222-
prev, curr = curr, curr.Next
223210
}
224211
if first == last {
225212
return []int{-1, -1}
@@ -244,30 +231,22 @@ func nodesBetweenCriticalPoints(head *ListNode) []int {
244231
*/
245232

246233
function nodesBetweenCriticalPoints(head: ListNode | null): number[] {
247-
let idx = 1;
248-
let pre = head.val;
249-
head = head.next;
250-
let nums = [];
251-
while (head.next != null) {
252-
let val = head.val,
253-
post = head.next.val;
254-
if (pre < val && val > post) {
255-
nums.push(idx);
256-
}
257-
if (pre > val && val < post) {
258-
nums.push(idx);
234+
const ans: number[] = [Infinity, 0];
235+
let [first, last] = [-1, -1];
236+
for (let i = 0; head.next.next; head = head.next, ++i) {
237+
const [a, b, c] = [head.val, head.next.val, head.next.next.val];
238+
if (b < Math.min(a, c) || b > Math.max(a, c)) {
239+
if (last < 0) {
240+
first = i;
241+
last = i;
242+
} else {
243+
ans[0] = Math.min(ans[0], i - last);
244+
last = i;
245+
ans[1] = Math.max(ans[1], last - first);
246+
}
259247
}
260-
pre = val;
261-
idx++;
262-
head = head.next;
263-
}
264-
let n = nums.length;
265-
if (n < 2) return [-1, -1];
266-
let min = Infinity;
267-
for (let i = 1; i < n; i++) {
268-
min = Math.min(nums[i] - nums[i - 1], min);
269248
}
270-
return [min, nums[n-1] -nums[0]];
249+
return first===last? [-1, -1] :ans;
271250
}
272251
```
273252

0 commit comments

Comments
(0)

AltStyle によって変換されたページ (->オリジナル) /