Runtime: 34 ms (Top 32.51%) | Memory: 13.40 MB (Top 25.91%)

Author: AnasImloul

scripts/algorithms/M/Minimum Insertions to Balance a Parentheses String/Minimum Insertions to Balance a Parentheses String.cpp

@@ -1,49 +1,29 @@
+// Runtime: 34 ms (Top 32.51%) | Memory: 13.40 MB (Top 25.91%)
+
 class Solution {
 public:
     int minInsertions(string s) {
-        stack<int> st;
-        int n = s.size();
-        int insert = 0;
-        for(int i = 0; i < n; i++)
-        {
-            if(s[i] == '(')
-            {
-                if(st.empty())
-                {
-                    st.push(2);
+        stack<char> v;
+        int ans = 0;
+        for(int i = 0;i < s.size();i++){
+            if(s[i] == '(') v.push(s[i]);
+            else{
+                if(s[i] == ')' && i < s.size() && s[i + 1] == ')') {
+                    if(!v.empty())
+                        v.pop();
+                    else ans++;
+                    i++;       // because we considered i+1 in this case
                 }
-                else
-                {
-                    if(st.top() != 2)
-                    {
-                        st.pop();
-                        insert++;
+                else if(s[i] == ')' && i < s.size() && s[i + 1] != ')'){
+                    if(!v.empty()){
+                        v.pop();
+                        ans++;
                     }
-                    st.push(2);
+                    else ans += 2;
                 }
             }
-            else
-            {
-                if(st.empty())
-                {
-                    insert++;
-                    st.push(1);
-                }
-                else
-                {
-                    int dummy = st.top();
-                    st.pop();
-                    dummy--;
-                    if(dummy)
-                        st.push(dummy);
-                }
-            }
-        }
-        while(!st.empty())
-        {
-            insert += st.top();
-            st.pop();
         }
-        return insert;
+        if(v.empty()) return ans;
+        return v.size()*2 + ans;
     }
 };