Skip to content

Commit 6bea4aa

Browse files
yanglbmeyanglbme
authored
feat: update lc problems (doocs#3697)
1 parent c310525 commit 6bea4aa

File tree

21 files changed

+239
-239
lines changed

21 files changed

+239
-239
lines changed

‎lcof2/剑指 Offer II 109. 开密码锁/README.md‎

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -289,12 +289,12 @@ class Solution {
289289
if target == "0000" {
290290
return 0
291291
}
292-
292+
293293
var visited = Set<String>()
294294
var queue = ["0000"]
295295
visited.insert("0000")
296296
var step = 0
297-
297+
298298
while !queue.isEmpty {
299299
step += 1
300300
for _ in 0..<queue.count {
@@ -311,10 +311,10 @@ class Solution {
311311
}
312312
}
313313
}
314-
314+
315315
return -1
316316
}
317-
317+
318318
private func getNeighbors(_ lock: String) -> [String] {
319319
var neighbors = [String]()
320320
var chars = Array(lock)
@@ -328,7 +328,7 @@ class Solution {
328328
}
329329
return neighbors
330330
}
331-
331+
332332
private func prevChar(_ c: Character) -> Character {
333333
return c == "0" ? "9" : Character(UnicodeScalar(c.asciiValue! - 1))
334334
}

‎lcof2/剑指 Offer II 110. 所有路径/README.md‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -208,7 +208,7 @@ class Solution {
208208
results.append(Array(path))
209209
return
210210
}
211-
211+
212212
for next in graph[node] {
213213
path.append(next)
214214
dfs(next, &path)

‎lcof2/剑指 Offer II 111. 计算除法/README.md‎

Lines changed: 12 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -298,23 +298,23 @@ func find(x int) int {
298298
class Solution {
299299
private var parent = [Int]()
300300
private var weight = [Double]()
301-
301+
302302
func calcEquation(
303-
_ equations: [[String]],
304-
_ values: [Double],
303+
_ equations: [[String]],
304+
_ values: [Double],
305305
_ queries: [[String]]
306306
) -> [Double] {
307307
let n = equations.count
308308
parent = Array(0..<(n * 2))
309309
weight = Array(repeating: 1.0, count: n * 2)
310-
310+
311311
var map = [String: Int]()
312312
var index = 0
313-
313+
314314
for i in 0..<n {
315315
let a = equations[i][0]
316316
let b = equations[i][1]
317-
317+
318318
if map[a] == nil {
319319
map[a] = index
320320
index += 1
@@ -323,18 +323,18 @@ class Solution {
323323
map[b] = index
324324
index += 1
325325
}
326-
326+
327327
let pa = find(map[a]!)
328328
let pb = find(map[b]!)
329-
329+
330330
if pa != pb {
331331
parent[pa] = pb
332332
weight[pa] = weight[map[b]!] * values[i] / weight[map[a]!]
333333
}
334334
}
335-
335+
336336
var result = [Double]()
337-
337+
338338
for query in queries {
339339
let (c, d) = (query[0], query[1])
340340
if let id1 = map[c], let id2 = map[d], find(id1) == find(id2) {
@@ -343,10 +343,10 @@ class Solution {
343343
result.append(-1.0)
344344
}
345345
}
346-
346+
347347
return result
348348
}
349-
349+
350350
private func find(_ x: Int) -> Int {
351351
if parent[x] != x {
352352
let origin = parent[x]

‎lcof2/剑指 Offer II 112. 最长递增路径/README.md‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -219,7 +219,7 @@ class Solution {
219219
m = matrix.count
220220
n = matrix[0].count
221221
memo = Array(repeating: Array(repeating: -1, count: n), count: m)
222-
222+
223223
var ans = 0
224224
for i in 0..<m {
225225
for j in 0..<n {
@@ -235,7 +235,7 @@ class Solution {
235235
}
236236
var ans = 1
237237
let dirs = [(-1, 0), (1, 0), (0, -1), (0, 1)]
238-
238+
239239
for (dx, dy) in dirs {
240240
let x = i + dx, y = j + dy
241241
if x >= 0, x < m, y >= 0, y < n, matrix[x][y] > matrix[i][j] {

‎lcof2/剑指 Offer II 113. 课程顺序/README.md‎

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -276,34 +276,34 @@ class Solution {
276276
func findOrder(_ numCourses: Int, _ prerequisites: [[Int]]) -> [Int] {
277277
var graph = Array(repeating: [Int](), count: numCourses)
278278
var indegree = Array(repeating: 0, count: numCourses)
279-
279+
280280
for prereq in prerequisites {
281281
let course = prereq[0]
282282
let prereqCourse = prereq[1]
283283
graph[prereqCourse].append(course)
284284
indegree[course] += 1
285285
}
286-
286+
287287
var queue = [Int]()
288288
for i in 0..<numCourses {
289289
if indegree[i] == 0 {
290290
queue.append(i)
291291
}
292292
}
293-
293+
294294
var order = [Int]()
295295
while !queue.isEmpty {
296296
let course = queue.removeFirst()
297297
order.append(course)
298-
298+
299299
for nextCourse in graph[course] {
300300
indegree[nextCourse] -= 1
301301
if indegree[nextCourse] == 0 {
302302
queue.append(nextCourse)
303303
}
304304
}
305305
}
306-
306+
307307
return order.count == numCourses ? order : []
308308
}
309309
}

‎lcof2/剑指 Offer II 114. 外星文字典/README.md‎

Lines changed: 8 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -358,7 +358,7 @@ class Solution {
358358
var indegree = Array(repeating: 0, count: 26)
359359
var seen = Array(repeating: false, count: 26)
360360
var letterCount = 0
361-
361+
362362
for i in 0..<words.count - 1 {
363363
for char in words[i] {
364364
let index = Int(char.asciiValue! - Character("a").asciiValue!)
@@ -371,39 +371,39 @@ class Solution {
371371
for j in 0..<minLength {
372372
let char1 = words[i][words[i].index(words[i].startIndex, offsetBy: j)]
373373
let char2 = words[i + 1][words[i + 1].index(words[i + 1].startIndex, offsetBy: j)]
374-
374+
375375
if char1 != char2 {
376376
let c1 = Int(char1.asciiValue! - Character("a").asciiValue!)
377377
let c2 = Int(char2.asciiValue! - Character("a").asciiValue!)
378-
378+
379379
if !graph[c1].contains(c2) {
380380
graph[c1].insert(c2)
381381
indegree[c2] += 1
382382
}
383383
break
384384
}
385-
385+
386386
if j == minLength - 1 && words[i].count > words[i + 1].count {
387387
return ""
388388
}
389389
}
390390
}
391-
391+
392392
for char in words[words.count - 1] {
393393
let index = Int(char.asciiValue! - Character("a").asciiValue!)
394394
if !seen[index] {
395395
seen[index] = true
396396
letterCount += 1
397397
}
398398
}
399-
399+
400400
var queue = [Int]()
401401
for i in 0..<26 {
402402
if seen[i] && indegree[i] == 0 {
403403
queue.append(i)
404404
}
405405
}
406-
406+
407407
var order = ""
408408
while !queue.isEmpty {
409409
let u = queue.removeFirst()
@@ -415,7 +415,7 @@ class Solution {
415415
}
416416
}
417417
}
418-
418+
419419
return order.count == letterCount ? order : ""
420420
}
421421
}

‎solution/2200-2299/2222.Number of Ways to Select Buildings/README.md‎

Lines changed: 58 additions & 54 deletions
Original file line numberDiff line numberDiff line change
@@ -74,11 +74,13 @@ tags:
7474

7575
<!-- solution:start -->
7676

77-
### 方法一：统计 010 和 101 的出现次数
77+
### 方法一：计数 + 枚举
7878

79-
有效方案只有两种情况：$010$ 和 $101$。枚举中间数字，累计方案数。
79+
根据题目描述，我们需要选择 $3$ 栋建筑，且相邻的两栋不能是同一类型。
8080

81-
时间复杂度 $O(n)$，其中 $n$ 表示 $s$ 的长度。
81+
我们可以枚举中间的建筑，假设为 $x$，那么左右两边的建筑类型只能是 $x \oplus 1$，其中 $\oplus$ 表示异或运算。因此，我们可以使用两个数组 $l$ 和 $r$ 分别记录左右两边的建筑类型的数量，然后枚举中间的建筑，计算答案即可。
82+
83+
时间复杂度 $O(n)$，其中 $n$ 是字符串 $s$ 的长度。空间复杂度 $O(1)$。
8284

8385
<!-- tabs:start -->
8486

@@ -87,18 +89,13 @@ tags:
8789
```python
8890
class Solution:
8991
def numberOfWays(self, s: str) -> int:
90-
n = len(s)
91-
cnt0 = s.count("0")
92-
cnt1 = n - cnt0
93-
c0 = c1 = 0
92+
l = [0, 0]
93+
r = [s.count("0"), s.count("1")]
9494
ans = 0
95-
for c in s:
96-
if c == "0":
97-
ans += c1 * (cnt1 - c1)
98-
c0 += 1
99-
else:
100-
ans += c0 * (cnt0 - c0)
101-
c1 += 1
95+
for x in map(int, s):
96+
r[x] -= 1
97+
ans += l[x ^ 1] * r[x ^ 1]
98+
l[x] += 1
10299
return ans
103100
```
104101

@@ -108,23 +105,17 @@ class Solution:
108105
class Solution {
109106
public long numberOfWays(String s) {
110107
int n = s.length();
111-
int cnt0 = 0;
112-
for (char c : s.toCharArray()) {
113-
if (c == '0') {
114-
++cnt0;
115-
}
108+
int[] l = new int[2];
109+
int[] r = new int[2];
110+
for (int i = 0; i < n; ++i) {
111+
r[s.charAt(i) - '0']++;
116112
}
117-
int cnt1 = n - cnt0;
118113
long ans = 0;
119-
int c0 = 0, c1 = 0;
120-
for (char c : s.toCharArray()) {
121-
if (c == '0') {
122-
ans += c1 * (cnt1 - c1);
123-
++c0;
124-
} else {
125-
ans += c0 * (cnt0 - c0);
126-
++c1;
127-
}
114+
for (int i = 0; i < n; ++i) {
115+
int x = s.charAt(i) - '0';
116+
r[x]--;
117+
ans += 1L * l[x ^ 1] * r[x ^ 1];
118+
l[x]++;
128119
}
129120
return ans;
130121
}
@@ -138,19 +129,16 @@ class Solution {
138129
public:
139130
long long numberOfWays(string s) {
140131
int n = s.size();
141-
int cnt0 = 0;
142-
for (char& c : s) cnt0 += c == '0';
143-
int cnt1 = n - cnt0;
144-
int c0 = 0, c1 = 0;
132+
int l[2]{};
133+
int r[2]{};
134+
r[0] = ranges::count(s, '0');
135+
r[1] = n - r[0];
145136
long long ans = 0;
146-
for (char& c : s) {
147-
if (c == '0') {
148-
ans += c1 * (cnt1 - c1);
149-
++c0;
150-
} else {
151-
ans += c0 * (cnt0 - c0);
152-
++c1;
153-
}
137+
for (int i = 0; i < n; ++i) {
138+
int x = s[i] - '0';
139+
r[x]--;
140+
ans += 1LL * l[x ^ 1] * r[x ^ 1];
141+
l[x]++;
154142
}
155143
return ans;
156144
}
@@ -160,22 +148,38 @@ public:
160148
#### Go
161149
162150
```go
163-
func numberOfWays(s string) int64 {
151+
func numberOfWays(s string) (ans int64) {
164152
n := len(s)
165-
cnt0 := strings.Count(s, "0")
166-
cnt1 := n - cnt0
167-
c0, c1 := 0, 0
168-
ans := 0
153+
l := [2]int{}
154+
r := [2]int{}
155+
r[0] = strings.Count(s, "0")
156+
r[1] = n - r[0]
169157
for _, c := range s {
170-
if c == '0' {
171-
ans += c1 * (cnt1 - c1)
172-
c0++
173-
} else {
174-
ans += c0 * (cnt0 - c0)
175-
c1++
176-
}
158+
x := int(c - '0')
159+
r[x]--
160+
ans += int64(l[x^1] * r[x^1])
161+
l[x]++
177162
}
178-
return int64(ans)
163+
return
164+
}
165+
```
166+
167+
#### TypeScript
168+
169+
```ts
170+
function numberOfWays(s: string): number {
171+
const n = s.length;
172+
const l: number[] = [0, 0];
173+
const r: number[] = [s.split('').filter(c => c === '0').length, 0];
174+
r[1] = n - r[0];
175+
let ans: number = 0;
176+
for (const c of s) {
177+
const x = c === '0' ? 0 : 1;
178+
r[x]--;
179+
ans += l[x ^ 1] * r[x ^ 1];
180+
l[x]++;
181+
}
182+
return ans;
179183
}
180184
```
181185

0 commit comments

Comments
 (0)