Add Atoi Iterative Solution

Author: Ashok-Bhatt

String_to_Integer_(atoi)/submission1.cpp

@@ -0,0 +1,42 @@
+class Solution {
+public:
+    int myAtoi(string s) {
+
+        // INT_MAX : 2147483647
+        // E.g.    : 2147483648
+        
+        int i = 0, n = s.size(), ans = 0, sign = 1;
+        bool isSymbolUsed = false;
+
+        while (i<n && s[i]==' '){
+            i++;
+        }
+
+        while (i<n){
+            char character = s[i];
+            if (character == '-' || character == '+'){
+                if (isSymbolUsed){
+                    break;
+                } else if (character == '-'){
+                    sign = -1;
+                }
+                isSymbolUsed = true;
+            } else if (character>='0' && character<='9'){
+                int digit = character - '0';
+                if ((ans > INT_MAX/10) || (ans==INT_MAX/10 && INT_MAX%10<=digit)){
+                    return INT_MAX;
+                } else if ((ans < INT_MIN/10) || (ans==INT_MIN/10 && (~INT_MIN%10+1)%10<=digit)){
+                    return INT_MIN;
+                } else {
+                    ans = ans*10 + sign*digit;
+                }
+                isSymbolUsed = true;
+            } else {
+                break;
+            }
+            i++;
+        }
+
+        return ans;
+    }
+};