Merge pull request larissalages#138 from PriyanshVerma/leetcode-cpp-all-anagrams-string

Find All Anagrams in a String

Author: larissalages

leetcode/cpp/string/438.cpp

@@ -0,0 +1,47 @@
+class Solution {
+public:
+    vector<int> findAnagrams(string s, string p) {
+        if (s.length() < p.length()) {
+            vector<int> v;
+            return v;
+        }
+        
+        unordered_map<char,int> t , m ;
+        for(char c : p) {
+            t[c]++;
+        }
+        for(int i=0;i<p.length();i++){
+            m[s[i]]++;
+        }
+        
+        vector<int> ans;
+        int st=0, en=p.length()-1;
+        while(en<s.length()) {
+            if (same(m,t)) {
+                ans.push_back(st);
+            }
+            acq(m, st, en, s);
+            rel(m, st, en, s);
+        }
+        //
+        return ans;
+    }
+    void acq(unordered_map<char,int> & m, int &st, int &en, string &str) {
+        en++;
+        if (en<str.length()) {
+            m[str[en]]++;
+        }
+    }
+    void rel(unordered_map<char,int> & m, int &st, int &en, string &str) {
+        m[str[st]]--;
+        if (m[str[st]]==0) m.erase(str[st]);
+        st++;
+    }
+    bool same(unordered_map<char,int> & m, unordered_map<char,int> & t) {
+        for(auto p : t) {
+            if (m[p.first] != p.second) 
+                return false;
+        }
+        return true;
+    }
+};