# Find repeated character present first in a string

Given a string, find the repeated character present first in the string.

(Not the first repeated character, found here.) Examples:

```Input  : geeksforgeeks
Output : g
(mind that it will be g, not e.)
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Simple Solution using O(N^2) complexity
The solution is to loop through the string for each character and search for the same in the rest of the string. This would need two loops and thus not optimal.

## C++

 `// C++ program to find the fist  ` `// character that is repeated ` `#include ` `#include ` ` `  `using` `namespace` `std; ` `int` `findRepeatFirstN2(``char``* s) ` `{ ` `    ``// this is O(N^2) method ` `    ``int` `p = -1, i, j; ` `    ``for` `(i = 0; i < ``strlen``(s); i++) ` `    ``{ ` `        ``for` `(j = i + 1; j < ``strlen``(s); j++) ` `        ``{ ` `            ``if` `(s[i] == s[j]) ` `            ``{ ` `                ``p = i; ` `                ``break``; ` `            ``} ` `        ``} ` `        ``if` `(p != -1) ` `            ``break``; ` `    ``} ` ` `  `    ``return` `p; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``char` `str[] = ``"geeksforgeeks"``; ` `    ``int` `pos = findRepeatFirstN2(str); ` `    ``if` `(pos == -1) ` `        ``cout << ``"Not found"``; ` `    ``else` `        ``cout << str[pos]; ` `    ``return` `0; ` `} ` ` `  `// This code is contributed  ` `// by Akanksha Rai `

## C

 `// C program to find the fist character that  ` `// is repeated ` `#include ` `#include ` ` `  `int` `findRepeatFirstN2(``char``* s) ` `{ ` `    ``// this is O(N^2) method ` `    ``int` `p = -1, i, j; ` `    ``for` `(i = 0; i < ``strlen``(s); i++) { ` `        ``for` `(j = i + 1; j < ``strlen``(s); j++) { ` `            ``if` `(s[i] == s[j]) { ` `                ``p = i; ` `                ``break``; ` `            ``} ` `        ``} ` `        ``if` `(p != -1) ` `            ``break``; ` `    ``} ` ` `  `    ``return` `p; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``char` `str[] = ``"geeksforgeeks"``; ` `    ``int` `pos = findRepeatFirstN2(str); ` `    ``if` `(pos == -1) ` `        ``printf``(``"Not found"``); ` `    ``else` `        ``printf``(``"%c"``, str[pos]); ` `    ``return` `0; ` `} `

## Java

 `// Java program to find the fist character ` `// that is repeated ` `import` `java.io.*; ` `import` `java.util.*; ` ` `  `class` `GFG { ` ` `  `    ``static` `int` `findRepeatFirstN2(String s) ` `    ``{ ` `         `  `        ``// this is O(N^2) method ` `        ``int` `p = -``1``, i, j; ` `        ``for` `(i = ``0``; i < s.length(); i++) ` `        ``{ ` `            ``for` `(j = i + ``1``; j < s.length(); j++) ` `            ``{ ` `                ``if` `(s.charAt(i) == s.charAt(j)) ` `                ``{ ` `                    ``p = i; ` `                    ``break``; ` `                ``} ` `            ``} ` `            ``if` `(p != -``1``) ` `                ``break``; ` `        ``} ` `     `  `        ``return` `p; ` `    ``} ` `     `  `    ``// Driver code ` `    ``static` `public` `void` `main (String[] args) ` `    ``{ ` `        ``String str = ``"geeksforgeeks"``; ` `        ``int` `pos = findRepeatFirstN2(str); ` `         `  `        ``if` `(pos == -``1``) ` `            ``System.out.println(``"Not found"``); ` `        ``else` `        ``System.out.println( str.charAt(pos)); ` `    ``} ` `} ` ` `  `// This code is contributed by anuj_67. `

## Python3

 `# Python3 program to find the fist  ` `# character that is repeated ` ` `  `def` `findRepeatFirstN2(s): ` ` `  `    ``# this is O(N^2) method ` `    ``p ``=` `-``1` `    ``for` `i ``in` `range``(``len``(s)): ` `     `  `        ``for` `j ``in` `range` `(i ``+` `1``, ``len``(s)): ` `         `  `            ``if` `(s[i] ``=``=` `s[j]): ` `                ``p ``=` `i ` `                ``break` `             `  `        ``if` `(p !``=` `-``1``): ` `            ``break` ` `  `    ``return` `p ` ` `  `# Driver code ` `if` `__name__ ``=``=` `"__main__"``: ` ` `  `    ``str` `=` `"geeksforgeeks"` `    ``pos ``=` `findRepeatFirstN2(``str``) ` `    ``if` `(pos ``=``=` `-``1``): ` `        ``print` `(``"Not found"``) ` `    ``else``: ` `        ``print` `(``str``[pos]) ` `     `  `# This code is contributed  ` `# by ChitraNayal `

## C#

 `// C# program to find the fist character ` `// that is repeated ` `using` `System; ` ` `  `class` `GFG { ` ` `  `    ``static` `int` `findRepeatFirstN2(``string` `s) ` `    ``{ ` `         `  `        ``// this is O(N^2) method ` `        ``int` `p = -1, i, j; ` `        ``for` `(i = 0; i < s.Length; i++) ` `        ``{ ` `            ``for` `(j = i + 1; j < s.Length; j++) ` `            ``{ ` `                ``if` `(s[i] == s[j]) ` `                ``{ ` `                    ``p = i; ` `                    ``break``; ` `                ``} ` `            ``} ` `            ``if` `(p != -1) ` `                ``break``; ` `        ``} ` `     `  `        ``return` `p; ` `    ``} ` `     `  `    ``// Driver code ` `    ``static` `public` `void` `Main () ` `    ``{ ` `        ``string` `str = ``"geeksforgeeks"``; ` `        ``int` `pos = findRepeatFirstN2(str); ` `         `  `        ``if` `(pos == -1) ` `            ``Console.WriteLine(``"Not found"``); ` `        ``else` `        ``Console.WriteLine( str[pos]); ` `    ``} ` `} ` ` `  `// This code is contributed by anuj_67. `

## PHP

 ` `

Output:

```g
```

Optimization by counting occurrences

This solution is optimized by using the following techniques:
1. We loop through the string and hash the characters using ASCII codes. Store 1 if found and store 2 if found again. Also, store the position of the letter first found in.

2. We run a loop on the hash array and now we find the minimum position of any character repeated.

This will have a runtime of O(N).

## C++

 `// C++ program to find the fist character that  ` `// is repeated ` `#include ` ` `  `using` `namespace` `std; ` `// 256 is taken just to ensure nothing is left, ` `// actual max ASCII limit is 128 ` `#define MAX_CHAR 256 ` ` `  `int` `findRepeatFirst(``char``* s) ` `{ ` `    ``// this is optimized method ` `    ``int` `p = -1, i, k; ` ` `  `    ``// initialized counts of occurrences of ` `    ``// elements as zero ` `    ``int` `hash[MAX_CHAR] = { 0 }; ` ` `  `    ``// initialized positions ` `    ``int` `pos[MAX_CHAR]; ` ` `  `    ``for` `(i = 0; i < ``strlen``(s); i++) { ` `        ``k = (``int``)s[i]; ` `        ``if` `(hash[k] == 0) { ` `            ``hash[k]++; ` `            ``pos[k] = i; ` `        ``} ``else` `if` `(hash[k] == 1) ` `            ``hash[k]++; ` `    ``} ` ` `  `    ``for` `(i = 0; i < MAX_CHAR; i++) { ` `        ``if` `(hash[i] == 2) { ` `            ``if` `(p == -1) ``// base case ` `                ``p = pos[i]; ` `            ``else` `if` `(p > pos[i]) ` `                ``p = pos[i]; ` `        ``} ` `    ``} ` ` `  `    ``return` `p; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``char` `str[] = ``"geeksforgeeks"``; ` `    ``int` `pos = findRepeatFirst(str); ` `    ``if` `(pos == -1) ` `        ``cout << ``"Not found"``; ` `    ``else` `        ``cout << str[pos]; ` `    ``return` `0; ` `} ` ` `  `// This code is contributed  ` `// by Akanksha Rai `

## C

 `// C program to find the fist character that  ` `// is repeated ` `#include ` `#include ` ` `  `// 256 is taken just to ensure nothing is left, ` `// actual max ASCII limit is 128 ` `#define MAX_CHAR 256 ` ` `  `int` `findRepeatFirst(``char``* s) ` `{ ` `    ``// this is optimized method ` `    ``int` `p = -1, i, k; ` ` `  `    ``// initialized counts of occurrences of ` `    ``// elements as zero ` `    ``int` `hash[MAX_CHAR] = { 0 }; ` ` `  `    ``// initialized positions ` `    ``int` `pos[MAX_CHAR]; ` ` `  `    ``for` `(i = 0; i < ``strlen``(s); i++) { ` `        ``k = (``int``)s[i]; ` `        ``if` `(hash[k] == 0) { ` `            ``hash[k]++; ` `            ``pos[k] = i; ` `        ``} ``else` `if` `(hash[k] == 1) ` `            ``hash[k]++; ` `    ``} ` ` `  `    ``for` `(i = 0; i < MAX_CHAR; i++) { ` `        ``if` `(hash[i] == 2) { ` `            ``if` `(p == -1) ``// base case ` `                ``p = pos[i]; ` `            ``else` `if` `(p > pos[i]) ` `                ``p = pos[i]; ` `        ``} ` `    ``} ` ` `  `    ``return` `p; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``char` `str[] = ``"geeksforgeeks"``; ` `    ``int` `pos = findRepeatFirst(str); ` `    ``if` `(pos == -1) ` `        ``printf``(``"Not found"``); ` `    ``else` `        ``printf``(``"%c"``, str[pos]); ` `    ``return` `0; ` `} `

## Java

 `// Java Program to find the fist character   ` `// that is repeated ` ` `  `import` `java.util.*; ` `import` `java.lang.*; ` ` `  `public` `class` `GFG ` `{ ` `    ``public` `static` `int` `findRepeatFirst(String s) ` `    ``{ ` `        ``// this is optimized method ` `        ``int` `p = -``1``, i, k; ` ` `  `        ``// initialized counts of occurrences of ` `        ``// elements as zero ` `        ``int` `MAX_CHAR = ``256``; ` `        ``int` `hash[] = ``new` `int``[MAX_CHAR]; ` ` `  `        ``// initialized positions ` `        ``int` `pos[] = ``new` `int``[MAX_CHAR]; ` ` `  `        ``for` `(i = ``0``; i < s.length(); i++) ` `        ``{ ` `            ``k = (``int``)s.charAt(i); ` `            ``if` `(hash[k] == ``0``) ` `            ``{ ` `                ``hash[k]++; ` `                ``pos[k] = i; ` `            ``} ` `            ``else` `if` `(hash[k] == ``1``) ` `                ``hash[k]++; ` `        ``} ` ` `  `        ``for` `(i = ``0``; i < MAX_CHAR; i++) ` `        ``{ ` `            ``if` `(hash[i] == ``2``) ` `            ``{ ` `                ``if` `(p == -``1``) ``// base case ` `                    ``p = pos[i]; ` `                ``else` `if` `(p > pos[i]) ` `                    ``p = pos[i]; ` `            ``} ` `        ``} ` ` `  `        ``return` `p; ` `    ``} ` ` `  `// Driver code ` `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` `        ``String str = ``"geeksforgeeks"``; ` `        ``int` `pos = findRepeatFirst(str); ` `        ``if` `(pos == -``1``) ` `            ``System.out.println(``"Not found"``); ` `        ``else` `            ``System.out.println(str.charAt(pos)); ` `    ``} ` `} ` ` `  `// Code Contributed by Mohit Gupta_OMG `

## Python3

 `# Python 3 program to find the fist  ` `# character that is repeated ` ` `  `# 256 is taken just to ensure nothing ` `# is left, actual max ASCII limit is 128 ` ` `  `MAX_CHAR ``=` `256` ` `  `def` `findRepeatFirst(s): ` `     `  `    ``# this is optimized method ` `    ``p ``=` `-``1` ` `  `    ``# initialized counts of occurrences  ` `    ``# of elements as zero ` `    ``hash` `=` `[``0` `for` `i ``in` `range``(MAX_CHAR)]  ` ` `  `    ``# initialized positions ` `    ``pos ``=` `[``0` `for` `i ``in` `range``(MAX_CHAR)] ` ` `  `    ``for` `i ``in` `range``(``len``(s)): ` `        ``k ``=` `ord``(s[i]) ` `        ``if` `(``hash``[k] ``=``=` `0``): ` `            ``hash``[k] ``+``=` `1` `            ``pos[k] ``=` `i ` `        ``elif``(``hash``[k] ``=``=` `1``): ` `            ``hash``[k] ``+``=` `1` ` `  `    ``for` `i ``in` `range``(MAX_CHAR): ` `        ``if` `(``hash``[i] ``=``=` `2``): ` `            ``if` `(p ``=``=` `-``1``): ``# base case ` `                ``p ``=` `pos[i] ` `            ``elif``(p > pos[i]): ` `                ``p ``=` `pos[i] ` `    ``return` `p ` ` `  `# Driver code ` `if` `__name__ ``=``=` `'__main__'``: ` `    ``str` `=` `"geeksforgeeks"` `    ``pos ``=` `findRepeatFirst(``str``); ` `    ``if` `(pos ``=``=` `-``1``): ` `        ``print``(``"Not found"``) ` `    ``else``: ` `        ``print``(``str``[pos]) ` `         `  `# This code is contributed by ` `# Shashank_Sharma `

## C#

 `// C# Program to find the fist character   ` `// that is repeated ` `using` `System; ` `public` `class` `GFG ` `{ ` `    ``public` `static` `int` `findRepeatFirst(``string` `s) ` `    ``{ ` `        ``// this is optimized method ` `        ``int` `p = -1, i, k; ` `  `  `        ``// initialized counts of occurrences of ` `        ``// elements as zero ` `        ``int` `MAX_CHAR = 256; ` `        ``int` `[]hash = ``new` `int``[MAX_CHAR]; ` `  `  `        ``// initialized positions ` `        ``int` `[]pos = ``new` `int``[MAX_CHAR]; ` `  `  `        ``for` `(i = 0; i < s.Length; i++) ` `        ``{ ` `            ``k = (``int``)s[i]; ` `            ``if` `(hash[k] == 0) ` `            ``{ ` `                ``hash[k]++; ` `                ``pos[k] = i; ` `            ``} ` `            ``else` `if` `(hash[k] == 1) ` `                ``hash[k]++; ` `        ``} ` `  `  `        ``for` `(i = 0; i < MAX_CHAR; i++) ` `        ``{ ` `            ``if` `(hash[i] == 2) ` `            ``{ ` `                ``if` `(p == -1) ``// base case ` `                    ``p = pos[i]; ` `                ``else` `if` `(p > pos[i]) ` `                    ``p = pos[i]; ` `            ``} ` `        ``} ` `  `  `        ``return` `p; ` `    ``} ` `  `  `    ``// Driver code ` `    ``public` `static` `void` `Main() ` `    ``{ ` `        ``string` `str = ``"geeksforgeeks"``; ` `        ``int` `pos = findRepeatFirst(str); ` `        ``if` `(pos == -1) ` `            ``Console.Write(``"Not found"``); ` `        ``else` `            ``Console.Write(str[pos]); ` `    ``} ` `} ` `  `  `// This code is contributed by nitin mittal. `

Output:

```g
```

More optimized Solution
Repeated Character Whose First Appearance is Leftmost

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