Create 752. Open the Lock (#462)

Author: Chayandas07

752. Open the Lock

@@ -0,0 +1,40 @@
+class Solution 
+{
+public:
+    int openLock(vector<string>& deadends, string target) 
+    {
+        int operations = 0;
+        unordered_set<string> dead, vis;
+
+        for(auto &deadend : deadends) dead.insert(deadend);
+        if(dead.count("0000")) return -1;
+
+        queue<string> q;
+        q.push("0000");
+        vis.insert("0000");
+
+        while(q.size())
+        {
+            int sz = q.size();
+            while(sz--)
+            {
+                string cur_state = q.front();q.pop();
+                if(cur_state == target) return operations;
+                for(int i = 0; i < 4; i++)
+                {
+                    string new_state = cur_state;
+                    new_state[i] == '9' ? new_state[i] = '0' : new_state[i]++;
+                    if(!vis.count(new_state) and !dead.count(new_state)) 
+                        q.push(new_state), vis.insert(new_state);
+
+                    new_state = cur_state;
+                    new_state[i] == '0' ? new_state[i] = '9' : new_state[i]--;
+                    if(!vis.count(new_state) and !dead.count(new_state)) 
+                        q.push(new_state), vis.insert(new_state);
+                }
+            }
+            operations++;
+        }
+        return -1;
+    }
+};