Solution to #17

Solutions/S17.cpp

@@ -0,0 +1,20 @@
+vector<int> findAnagrams(string s, string p) {
+    vector<int> res;
+    int fre[26] = {0};
+    if(s.size() < p.size()) return res;
+    for(char c: p) {fre[c-'a']++;}
+    int st = 0, end = 0, cnt = p.size();
+    while(end < s.size())
+    {
+        //Two pointer approach
+        // If the starting character appeared in p, increment and move start pointer
+        if(end - st == p.size() && fre[s[st++] - 'a']++ >= 0) cnt++;
+
+        //If ending character appeared in p {since it's not < 0}, decrement and move end pointer
+        if(--fre[s[end++]-'a'] >= 0) cnt--;
+
+        //We have found one occurrence/match, since entire pattern size exhausted
+        if(cnt == 0) res.push_back(st);
+    }
+    return res;
+}