chore(Java): add isomorphic strings (#828)

* chore(Java): added isomorphic strings

* added Time and space complexity

* update algorithms/Java/README.md

* update algorithms/Java/README.md file

* spelling Correct README.md file

algorithms/Java/README.md

@@ -88,6 +88,7 @@
 - [Boyer Moore Search](strings/Boyer_Moore.java)
 - [Reverse String](strings/reverse-string.java)
 - [First Non Repeating Character](strings/first-non-repeating-char.java)
+- [Isomorphic Strings](strings/isomorphic_strings.java)
 
 ## Trees
 

algorithms/Java/strings/isomorphic_strings.java

@@ -0,0 +1,61 @@
+/** 
+    problem statement:
+    Given two strings- str1 and str2, check both are isomorphic or not
+    Isomorphic strings: Two strings are called isomorphic,
+    if there is a one to one mapping possible for every character of str1 to every character of str2 while preserving the order. 
+ */
+
+ /***
+    Example 1 => Input: str1="aab", str2="xxy"
+                 Output: 1
+    Example 2 => Input: str1="aab", str2="xyz"
+                 Output: 0
+  */
+/** 
+ * 
+ * Time Complexity: O(N)
+  Space Complexity: O(1)
+*/
+  
+  import java.util.Arrays;
+import java.util.Scanner;
+  public class isomorphic_strings{
+    public static void main(String[] args){
+        Scanner input=new Scanner(System.in);
+        String str1=input.next();
+        String str2=input.next();
+        if(strings_are_isomorphic(str1,str2)){
+            System.out.println("1");
+        }else{
+            System.out.println("0");
+        }
+    }
+    public static boolean strings_are_isomorphic(String s1,String s2){
+        int n=s1.length();
+        int m=s2.length();
+        //check length of both strings
+        if(n!=m){
+            return false;
+        }
+        // array, make for mark visited characters of s2.
+        boolean visited[]=new boolean[256];
+        //array, store mapping of every character from s1 to s2
+        int map[]=new int[256];
+        Arrays.fill(map,-1);
+        for (int i=0;i<n;i++)
+        {
+            char c1=s1.charAt(i);
+            char c2=s2.charAt(i);
+            if(map[c1]==-1){
+                if(visited[c2]==true){
+                    return false;
+                }
+                visited[c2]=true;
+                map[c1]=c2;
+            }else if(map[c1]!=c2){
+                return false;
+            }
+        }
+        return true;
+    }
+  }