6

The Last Algorithms Course You'll Need/6. Bubble Sort.c

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+#include <stdio.h>
+
+#define SIZE 10 
+
+// complexity is O(n^2)
+// how is that calculated?
+// well we run two loops, even if the first one is N
+// the second one is first N, then N - 1, then N - 2, ...
+// all the way down to N - N + 1
+// what's the sum of them? 
+// imagine sum of all form 1 to 100
+// okay, 1 + 100 = 101
+// okay, 2 + 99 = 101
+// etc all the way down to 50 and 51,
+// so we have 50 times 101 to calculate sum of 1 to 100
+// which means:
+// 101 * 50    or
+// (N+1) * N/2   or
+// N^2 + N    which makes
+// O(N^2 + N)   then we drop the non-significant + N
+// O(N^2)
+
+void bubble_sort(int array[], int size)
+{
+	int shift = 0;
+	for (int i = 1; i < size; ++i)
+	{
+		for (int j = 1; j < size - shift; ++j)
+		{
+			if (array[j] < array[j-1])
+			{
+				int temp = array[j];
+				array[j] = array[j-1];
+				array[j-1] = temp;
+			}
+		}
+		++shift;
+	}
+}
+
+int main()
+{
+	int array[SIZE] = { 5, 7, 3, 2, 11, 16, 1, 4, 3, 2 };
+	bubble_sort(array, SIZE);
+	for (int i = 0; i < SIZE; ++i)
+		printf("%d ", array[i]);
+	printf("\n");
+}