Implement the myAtoi(string s) function, which converts a string to a 32-bit signed integer (similar to C/C++'s atoi function) (#178)

* String to Integer converter like ATOI in C/C++

Implement the myAtoi(string s) function, which converts a string to a 32-bit signed integer (similar to C/C++'s atoi function)

* Rename Java file as per standard and add details to .md file

Rename Java file as per standard and add details to .md file

Author: sachsbu

Java/string-to-integer-atoi.java

@@ -0,0 +1,65 @@
+package com.bst.myexamples;
+
+/**
+ * Solution accepted on Leetcode with 7ms runtime and 39.2MB memory
+ *
+ * String to Integer (atoi)
+ * Implement the myAtoi(string s) function, which converts a string to a 32-bit signed integer (similar to C/C++'s atoi function).
+ * Approach
+ * 1.Prepare String that is having only +- sign and number value
+ * Convert to BigInteger to compare value with 32bit signed Integer range and clamp if goes out of range
+ * return output with 0 if no string number found or non number value found before any number value
+ */
+
+import java.math.*;
+class StringToIntegerATOI {
+
+    public static void main(String[] args){
+      /* StringToIntegerATOI sta = new StringToIntegerATOI();
+        System.out.println(sta.myAtoi("-20000000000000"));
+*/
+
+    }
+    public int myAtoi(String s) {
+
+        StringBuilder sb = new StringBuilder();
+
+        for(int i=0; i<s.length(); i++){
+
+            if(sb.length() == 0){
+                if(Character.isWhitespace(s.charAt(i)))
+                    continue;
+
+                if('-' == s.charAt(i)){
+                    sb.append("-");
+                    continue;
+                }
+
+                if('+' == s.charAt(i)){
+                    sb.append("+");
+                    continue;
+                }
+            }
+
+            if(Character.isDigit(s.charAt(i)))
+                sb.append(s.charAt(i));
+            else
+                break;
+
+        }
+
+        String val = sb.toString().replace("+","");
+
+        if(val.length() == 0 || val.equals("-"))
+            val="0";
+
+        BigInteger lvar = new BigInteger(val);
+
+        if(lvar.compareTo(BigInteger.valueOf(Integer.MAX_VALUE)) > 0)
+            lvar = BigInteger.valueOf(Integer.MAX_VALUE);
+        else if(lvar.compareTo(BigInteger.valueOf(Integer.MIN_VALUE)) < 0)
+            lvar = BigInteger.valueOf(Integer.MIN_VALUE);
+
+        return lvar.intValue();
+    }
+}

README.md

@@ -165,7 +165,7 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
 | 859  | [Buddy Strings](https://leetcode.com/problems/buddy-strings/)                                                                                   | [Java](./Java/buddy-strings.java)                                          | _O(n)_ | _O(1)_ | Easy       |     |                 |
 | 9    | [Palindrome Number](https://leetcode.com/problems/palindrome-number/)                                                                           | [Java](./Java/palindrome-number.java)                                      | _O(n)_ | _O(1)_ | Easy       |     |                 |
 | 767  | [Reorganize String](https://leetcode.com/problems/reorganize-string/)                                                                           | [Python](./Python/reorganize-string.py)                                    | _O(n)_ | _O(n)_ | Medium     |     |                 |
-
+| 8    | [String to Integer (atoi)](https://leetcode.com/problems/string-to-integer-atoi/)                                                               | [Java](./Java/string-to-integer-atoi.java)                                 | _O(n)_ | _O(1)_ | Medium     |     |                 |
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@@ -490,7 +490,7 @@ DISCLAIMER: This above mentioned resources have affiliate links, which means if
 | [Aysia](https://www.linkedin.com/in/aysiaelise/) <br> <img src="https://avatars.githubusercontent.com/u/70167431?s=460&u=1637be8636b6db6e35343ed9c1318c23e909b463&v=4" width="100" height="100">   | USA            | JavaScript           | [GitHub](https://github.com/aysiae)                                                                                                                                                                                         |
 | [Poorvi Garg](https://github.com/POORVI111) <br> <img src="https://avatars.githubusercontent.com/u/68559217?s=400&v=4" width="100" height="100">                                                   | India          | C++                  | [GitHub](https://github.com/POORVI111)                                                                                                                                                                                      |
 | [Lakshmanan Meiyappan](https://laxmena.com) <br> <img src="https://avatars.githubusercontent.com/u/12819059?s=400&v=4" width="100" height="100">                                                   | India          | C++                  | [Website - Blog](https://laxmena.com)<br/> [GitHub](https://github.com/laxmena) <br/> [LinekdIn](https://www.linkedin.com/in/lakshmanan-meiyappan/)                                                                         |
-
+| [Sachin_Upadhyay](https://github.com/sachsbu) <br> <img src="https://avatars.githubusercontent.com/u/24941685?v=4" width="100" height="100">                                                                   | India          | Java                  |  [GitHub](https://github.com/sachsbu)                                                                        |
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