Create: 0008-string-to-integer

cpp/0008-string-to-integer.cpp

@@ -0,0 +1,78 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+/*
+Implement the myAtoi(string s) function, which converts a string to a 32-bit signed integer.
+
+The algorithm for myAtoi(string s) is as follows:
+
+Whitespace: Ignore any leading whitespace (" ").
+Signedness: Determine the sign by checking if the next character is '-' or '+', assuming positivity if neither present.
+Conversion: Read the integer by skipping leading zeros until a non-digit character is encountered or the end of the string is reached. If no digits were read, then the result is 0.
+Rounding: If the integer is out of the 32-bit signed integer range [-231, 231 - 1], then round the integer to remain in the range. Specifically, integers less than -231 should be rounded to -231, and integers greater than 231 - 1 should be rounded to 231 - 1.
+Return the integer as the final result.
+Example :
+
+Input: s = " -042"
+
+Output: -42
+
+Explanation:
+
+Step 1: "   -042" (leading whitespace is read and ignored)
+            ^
+Step 2: "   -042" ('-' is read, so the result should be negative)
+             ^
+Step 3: "   -042" ("042" is read in, leading zeros ignored in the result)
+*/
+
+class Solution {
+    public:
+        int myAtoi(string s) {
+            int sign=1;
+            bool tag=false;
+            int j=0,ind;
+            double ans=0;
+
+            // trim the string till we get number
+            for (int i=0;i<s.size();i++){
+                if (s[i]==' ') {
+
+                    continue;}
+                else{ 
+                if (s[i]=='-') {
+                    sign =-1;
+                    j=i+1;
+                    break;
+                }
+                else if(s[i]=='+'){
+                    sign=1;
+                    j=i+1;
+                    break;
+                }
+                else{
+                    j=i;
+                    break;
+                }
+                }
+        }
+
+        // convert string to integer
+
+            for (int i=j;i<s.size();i++){
+                 if (int(s[i])>47 && int(s[i])<58){
+                    ans=ans*10;
+                    ans=ans+int(s[i])-48;
+
+                }
+                else {
+                    break;
+                }
+            }
+             ans=sign*ans;
+            long long y=pow(2,31);
+             if (ans <-1*y) return -1*y;
+             else if (ans > y-1) return y-1;
+            else return ans;
+        }
+    };

python/0008-string-to-integer.py

@@ -0,0 +1,51 @@
+'''
+Implement the myAtoi(string s) function, which converts a string to a 32-bit signed integer.
+
+The algorithm for myAtoi(string s) is as follows:
+
+Whitespace: Ignore any leading whitespace (" ").
+Signedness: Determine the sign by checking if the next character is '-' or '+', assuming positivity if neither present.
+Conversion: Read the integer by skipping leading zeros until a non-digit character is encountered or the end of the string is reached. If no digits were read, then the result is 0.
+Rounding: If the integer is out of the 32-bit signed integer range [-231, 231 - 1], then round the integer to remain in the range. Specifically, integers less than -231 should be rounded to -231, and integers greater than 231 - 1 should be rounded to 231 - 1.
+Return the integer as the final result.
+Example :
+
+Input: s = " -042"
+
+Output: -42
+
+Explanation:
+
+Step 1: "   -042" (leading whitespace is read and ignored)
+            ^
+Step 2: "   -042" ('-' is read, so the result should be negative)
+             ^
+Step 3: "   -042" ("042" is read in, leading zeros ignored in the result)
+'''
+
+class Solution:
+    def myAtoi(self, s: str) -> int:
+        s=s.strip()
+        sign=1
+        if len(s)==0:
+            return 0
+
+        if s[0]=="-" or s[0]=="+" :
+            sign=-1 if s[0]=="-" else 1
+            s=s[1:]
+
+        l=0 
+        for c in s:
+            k=ord(c)-48
+            if k in range(0,10):
+                l=l*10
+                l=l+k
+            else:
+                break
+
+        n=sign*l
+        if n>=(2**31):
+            return (2**31)-1
+        elif n<(-(2**31)):
+            return -(2**31)
+        return n