Time: 10 ms (13.15%), Space: 7 MB (24.93%) - LeetHub

0093-restore-ip-addresses/0093-restore-ip-addresses.cpp

@@ -0,0 +1,58 @@
+class Solution {
+public:
+    vector<string> ans;
+    string str="";
+    void solve(string s, int i,int k)
+    {
+        //base case
+        if(k==4 && i>=s.size())
+        {
+            str.pop_back();
+            ans.push_back(str);
+            str +='.';
+        }
+        if(k>4)return;
+
+
+        //take 1
+         if(i<s.size()){
+
+            str+=s[i];
+            str+=".";
+            solve(s,i+1,k+1);
+
+            str.pop_back();
+            str.pop_back();
+
+         }
+        //take 2
+        if(i+1<s.size() && s[i]!='0')
+        {
+            str+=s[i];
+            str+=s[i+1];
+            str+=".";
+            solve(s,i+2,k+1);
+            str.pop_back();
+            str.pop_back();
+            str.pop_back();
+        }
+        //take 3
+        if(i+2<s.size() && s[i]!='0' && stoi(s.substr(i, 3)) <= 255)
+        {
+            str+=s[i];
+            str+=s[i+1];
+            str+=s[i+2];
+            str+=".";
+            solve(s,i+3,k+1);
+            str.pop_back();
+            str.pop_back();
+            str.pop_back();
+            str.pop_back();
+        }
+        return;
+    }
+    vector<string> restoreIpAddresses(string s) {
+       solve(s,0,0);
+       return ans; 
+    }
+};