7777
7878<!-- solution:start -->
7979
80- ### 方法一
80+ ### 方法一:模拟
81+ 82+ 我们首先将句子按空格分割成单词,然后对每个单词进行检查,判断是否为有效单词。
83+ 84+ 对于每个单词,我们可以使用一个布尔变量 $\textit{st}$ 来记录是否已经出现过连字符,然后遍历单词中的每个字符,根据题目描述的规则进行判断。
85+ 86+ 对于每个字符 $s[ i] ,ドル我们有以下几种情况:
87+ 88+ - 如果 $s[ i] $ 是数字,那么 $s$ 不是有效单词,直接返回 $\text{false}$;
89+ - 如果 $s[ i] $ 是标点符号('!'、'.'、',')且 $i < \text{len}(s) - 1,ドル那么 $s$ 不是有效单词,直接返回 $\text{false}$;
90+ - 如果 $s[ i] $ 是连字符,那么我们需要判断是否满足以下条件:
91+ - 连字符只能出现一次;
92+ - 连字符不能出现在单词的开头或结尾;
93+ - 连字符两侧必须是字母;
94+ - 如果 $s[ i] $ 是字母,那么我们不需要做任何处理。
95+ 96+ 最后,我们统计出句子中的有效单词数即可。
97+ 98+ 时间复杂度 $O(n),ドル空间复杂度 $O(n)$。其中 $n$ 是句子的长度。
8199
82100<!-- tabs:start -->
83101
@@ -86,24 +104,23 @@ tags:
86104``` python
87105class Solution :
88106 def countValidWords (self sentence : str ) -> int :
89- def check (token ) :
90- hyphen = False
91- for i, c in enumerate (token ):
92- if c.isdigit() or (c in ' !.,' and i < len (token ) - 1 ):
107+ def check (s : str ) -> bool :
108+ st = False
109+ for i, c in enumerate (s ):
110+ if c.isdigit() or (c in " !.," and i < len (s ) - 1 ):
93111 return False
94- if c == ' - '
112+ if c == " - "
95113 if (
96- hyphen
97- or i == 0
98- or i == len (token) - 1
99- or not token[i - 1 ].islower()
100- or not token[i + 1 ].islower()
114+ st
115+ or i in (0 , len (s) - 1 )
116+ or not s[i - 1 ].isalpha()
117+ or not s[i + 1 ].isalpha()
101118 ):
102119 return False
103- hyphen = True
120+ st = True
104121 return True
105122
106- return sum (check(token ) for token in sentence.split())
123+ return sum (check(s ) for s in sentence.split())
107124```
108125
109126#### Java
@@ -112,76 +129,142 @@ class Solution:
112129class Solution {
113130 public int countValidWords (String sentence ) {
114131 int ans = 0 ;
115- for (String token : sentence. split(" "
116- if (check(token)) {
117- ++ ans;
118- }
132+ for (String s : sentence. split(" "
133+ ans += check(s. toCharArray());
119134 }
120135 return ans;
121136 }
122137
123- private boolean check (String token ) {
124- int n = token. length();
125- if (n == 0 ) {
126- return false ;
138+ private int check (char [] s ) {
139+ if (s. length == 0 ) {
140+ return 0 ;
127141 }
128- boolean hyphen = false ;
129- for (int i = 0 ; i < n; ++ i) {
130- char c = token. charAt(i);
131- if (Character . isDigit(c) || (i < n - 1 && (c == ' !' || c == ' .' || c == ' ,'
132- return false ;
142+ boolean st = false ;
143+ for (int i = 0 ; i < s. length; ++ i) {
144+ if (Character . isDigit(s[i])) {
145+ return 0 ;
146+ }
147+ if ((s[i] == ' !' || s[i] == ' .' || s[i] == ' ,' && i < s. length - 1 ) {
148+ return 0 ;
133149 }
134- if (c == ' -'
135- if (hyphen || i == 0 || i == n - 1 || ! Character . isLetter(token. charAt(i - 1 ))
136- || ! Character . isLetter(token. charAt(i + 1 ))) {
137- return false ;
150+ if (s[i] == ' -'
151+ if (st || i == 0 || i == s. length - 1 ) {
152+ return 0 ;
138153 }
139- hyphen = true ;
154+ if (! Character . isAlphabetic(s[i - 1 ]) || ! Character . isAlphabetic(s[i + 1 ])) {
155+ return 0 ;
156+ }
157+ st = true ;
140158 }
141159 }
142- return true ;
160+ return 1 ;
143161 }
144162}
145163```
146164
147- #### TypeScript
165+ #### C++
148166
149- ``` ts
150- function countValidWords(sentence : string ): number {
151- let words = sentence .trim ().split (/ \s + /
152- let ans = 0 ;
153- for (let word of words ) {
154- if (isValied (word )) {
155- ans ++ ;
167+ ``` cpp
168+ class Solution {
169+ public:
170+ int countValidWords(string sentence) {
171+ auto check = [ ] (const string& s) -> int {
172+ bool st = false;
173+ for (int i = 0; i < s.length(); ++i) {
174+ if (isdigit(s[ i] )) {
175+ return 0;
176+ }
177+ if ((s[ i] == '!' || s[ i] == '.' || s[ i] == ',') && i < s.length() - 1) {
178+ return 0;
179+ }
180+ if (s[ i] == '-') {
181+ if (st || i == 0 || i == s.length() - 1) {
182+ return 0;
183+ }
184+ if (!isalpha(s[ i - 1] ) || !isalpha(s[ i + 1] )) {
185+ return 0;
186+ }
187+ st = true;
188+ }
189+ }
190+ return 1;
191+ };
192+ 193+ int ans = 0;
194+ stringstream ss(sentence);
195+ string s;
196+ while (ss >> s) {
197+ ans += check(s);
156198 }
199+ return ans;
157200 }
158- return ans ;
201+ };
202+ ```
203+ 204+ #### Go
205+ 206+ ``` go
207+ func countValidWords (sentence string ) (ans int ) {
208+ check := func (s string ) int {
209+ if len (s) == 0 {
210+ return 0
211+ }
212+ st := false
213+ for i , r := range s {
214+ if unicode.IsDigit (r) {
215+ return 0
216+ }
217+ if (r == ' !' ' .' ' ,' len (s)-1 {
218+ return 0
219+ }
220+ if r == ' -'
221+ if st || i == 0 || i == len (s)-1 {
222+ return 0
223+ }
224+ if !unicode.IsLetter (rune (s[i-1 ])) || !unicode.IsLetter (rune (s[i+1 ])) {
225+ return 0
226+ }
227+ st = true
228+ }
229+ }
230+ return 1
231+ }
232+ for _ , s := range strings.Fields (sentence) {
233+ ans += check (s)
234+ }
235+ return ans
159236}
237+ ```
238+ 239+ #### TypeScript
160240
161- function isValied(str : string ): boolean {
162- let n = str .length ;
163- let hasLine = false ;
164- for (let i = 0 ; i < n ; i ++ ) {
165- const = str .charAt (i );
166- if (/ ^ [0-9 ] $ / test (char )) {
167- return false ;
241+ ``` ts
242+ function countValidWords(sentence : string ): number {
243+ const = (s : string ): number => {
244+ if (s .length === 0 ) {
245+ return 0 ;
168246 }
169- if ( char == ' - ' ) {
170- if ( hasLine ) return false ;
171- else {
172- hasLine = true ;
247+ let st = false ;
248+ for ( let i = 0 ; i < s . length ; ++ i ) {
249+ if ( / \d / . test ( s [ i ])) {
250+ return 0 ;
173251 }
174- let pre = str .charAt (i - 1 ),
175- post = str .charAt (i + 1 );
176- if (! / ^ [a-z ] $ / g test (pre ) || ! / ^ [a-z ] $ / g test (post )) {
177- return false ;
252+ if ([' !' ' .' ' ,' includes (s [i ]) && i < s .length - 1 ) {
253+ return 0 ;
254+ }
255+ if (s [i ] === ' -'
256+ if (st || [0 , s .length - 1 ].includes (i )) {
257+ return 0 ;
258+ }
259+ if (! / [a-zA-Z ] / test (s [i - 1 ]) || ! / [a-zA-Z ] / test (s [i + 1 ])) {
260+ return 0 ;
261+ }
262+ st = true ;
178263 }
179264 }
180- if (/ ^ [\!\.,円 \s ] $ / test (char ) && i != n - 1 ) {
181- return false ;
182- }
183- }
184- return true ;
265+ return 1 ;
266+ };
267+ return sentence .split (/ \s + / reduce ((acc , s ) => acc + check (s ), 0 );
185268}
186269```
187270
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