Create Basic Calculator.cpp

Author: Ayushluthra2001

Basic Calculator.cpp

@@ -0,0 +1,49 @@
+class Solution {
+public:
+    int calculate(string s) {
+        int result=0;
+        int sum=0;
+        int sign=1;
+        stack<int>st;
+        int n=s.size();
+        for(int i=0;i<n;i++)
+        {
+            if(isdigit(s[i]))
+            {
+                sum=s[i] -'0';
+                while(i+1<n && isdigit(s[i+1]))
+                {
+                    sum = sum*10 + (s[i+1] -'0');
+                    i++;
+                }
+                result+=sum*sign;
+            }
+            
+            else if(s[i] == '+')
+            {
+                sign=1;
+            }
+            else if (s[i] == '-')
+            {
+                sign=-1;
+            }
+            else if (s[i] == '(')
+            {
+                st.push(result);
+                st.push(sign);
+                result=0;
+                sign=1;
+            }
+            else if(s[i] == ')')
+            {
+                int xsign=st.top();
+                st.pop();
+                int xresult= st.top();
+                st.pop();
+                result=result*xsign + xresult;
+            }
+        }
+        
+        return result;
+    }
+};