From 74b541a1a07aa00eb360266ed2b72228380d47ae Mon Sep 17 00:00:00 2001
From: Fabrice <fabrice.reintsch@gmail.com>
Date: Fri, 5 Dec 2025 08:05:57 +0100
Subject: [PATCH] numbers.c angafangen

---
 main.c    |  2 +-
 numbers.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/main.c b/main.c
index 34163d0..9ede66b 100644
--- a/main.c
+++ b/main.c
@@ -67,7 +67,7 @@ int main(int argc, char *argv[])
         userInput = inputNumber("Welche Zahl kommt doppelt vor: ");
         measuredSeconds = stopTimer();
 
-        duplicate = getDuplicate(numbers, numberOfElements);
+        duplicate = getDuplicate(numbers, numberOfElements+1);
 
         // check result and update highscores
         if(userInput == duplicate)
diff --git a/numbers.c b/numbers.c
index f59d9a2..3671c88 100644
--- a/numbers.c
+++ b/numbers.c
@@ -16,11 +16,60 @@
 // creating random numbers.
 unsigned int *createNumbers(unsigned int len)
 {
+  srand(time(NULL));
 
+  unsigned int *numbers = malloc (sizeof(unsigned int) * (len+1));
+  unsigned int newNumber;
+
+  for (unsigned int i = 0; i < len; i++) {
+    int unique = 0;
+
+    while (!unique) {
+    unique = 1;
+    newNumber = rand () % (2*len) + 1;
+
+      for (unsigned int j = 0; j < i; j++) {
+        if (numbers[j] == newNumber) {
+          unique = 0;
+          break;
+        }
+      }
+    }
+    numbers[i] = newNumber;
+  }
+
+  unsigned int duplicate = numbers[rand () % len]; 
+  numbers[len] = duplicate;
+
+  return numbers;
 }
 
+int compare (const void *a, const void *b) {
+  unsigned int *x = a;
+  unsigned int *y = b;
+  if (*x < *y) {
+    return -1;
+  }
+  else if (*x > *y) {
+    return 1;
+  }
+  else {
+    return 0;
+  }
+}
 // Returns only the only number in numbers which is present twice. Returns zero on errors.
-unsigned int getDuplicate(const unsigned int numbers[], unsigned int len)
+unsigned int getDuplicate(unsigned int numbers[], unsigned int lenPlusOne)
 {
+  if (lenPlusOne < 2) {
+    return 0;
+  }
 
+qsort(numbers,lenPlusOne, sizeof(unsigned int), compare);
+
+for (int i = 0; i < lenPlusOne-1; i++) {
+  if (numbers[i] == numbers [i+1]) {
+    return numbers[i];
+  }
+}
+  return 0;
 }
\ No newline at end of file