Create number-of-valid-words-in-a-sentence.cpp

Author: kamyu104

C++/number-of-valid-words-in-a-sentence.cpp

@@ -0,0 +1,31 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    int countValidWords(string sentence) {
+        int result = 0, token = 0, hyphen = 0;
+        for (int i = 0; i <= size(sentence); ++i) {
+            if (i == size(sentence) || sentence[i] == ' ') {
+                if (token == 1) {
+                    ++result;
+                }
+                token = hyphen = 0;
+                continue;
+            }
+            if (isdigit(sentence[i]) ||
+                (string("!.,").find(sentence[i]) != string::npos && !(i == size(sentence) - 1 || sentence[i + 1] == ' ')) ||
+                (sentence[i] == '-' && !(hyphen == 0 && 0 < i && i < size(sentence) && isalpha(sentence[i - 1]) && isalpha(sentence[i + 1])))) {
+                token = -1;
+                continue;
+            }
+            if (token == 0) {
+                token = 1;
+            }
+            if (sentence[i] == '-') {
+                hyphen = 1;
+            }
+        }
+        return result;
+    }
+};