Create vowels-of-all-substrings.cpp

Author: kamyu104

C++/vowels-of-all-substrings.cpp

@@ -0,0 +1,17 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    long long countVowels(string word) {
+        static const unordered_set<char> VOWELS = {'a', 'e', 'i', 'o', 'u'};
+
+        int64_t result = 0;
+        for (int i = 0; i < size(word); ++i) {
+            if (VOWELS.count(word[i])) {
+                result += (i - 0 + 1)* ((size(word) - 1) - i + 1);
+            }
+        }
+        return result;
+    }
+};