Optimisation of myAtoi [1]

String to Integer (atoi)/myAtoi_optimistaion_1.py

@@ -0,0 +1,56 @@
+def helper(s,i):
+    l=len(s)
+    s1=""
+    for i in range(i,l):
+        if(s[i].isdigit()):
+            s1+=s[i]
+        else:
+            break
+
+    if s1=="":
+        s1=0
+
+    n=int(s1)
+
+    if s[0]=='-':
+        n=-n
+
+    if n<(-2)**31:
+        return (-2)**31
+    elif (2**31)-1<=n:
+        return (2**31)-1
+        #clamp the integer
+    else:
+        return n
+
+
+def myAtoi_optimisation_1(s) -> int:
+    s=s.lstrip() #Step-1
+
+    l=len(s)
+
+    if l==0:
+        return 0
+    else:
+        s1=""
+        #while l>0:
+        if not(s[0].isdigit() or s[0]=='-' or s[0]=='+'):
+            return 0
+        elif s[0]=='-' or s[0]=='+':
+            res=helper(s,1)
+        elif s[0].isdigit():
+            res=helper(s,0)
+
+        return res
+
+
+if __name__=="__main__":
+    print(myAtoi_optimisation_1("42")) # 42
+    print(myAtoi_optimisation_1("-42")) # -42
+    print(myAtoi_optimisation_1("4193 with words")) # 4193
+    print(myAtoi_optimisation_1("words and 987")) # 0
+    print(myAtoi_optimisation_1("-91283472332")) # -2147483648
+    print(myAtoi_optimisation_1("3.14159")) # 3
+    print(myAtoi_optimisation_1(".1")) # 0
+    print(myAtoi_optimisation_1("21474836460")) # 2147483647
+    print(myAtoi_optimisation_1("+-12")) # 0