Add 0912

Signed-off-by: begeekmyfriend <begeekmyfriend@gmail.com>

Author: begeekmyfriend

0912_sort_an_array/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -o test sort.c

0912_sort_an_array/sort.c

@@ -0,0 +1,67 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+
+static void show(int *nums, int lo, int hi)
+{
+        int i;
+        for (i = lo; i <= hi; i++) {
+                printf("%d ", nums[i]);
+        }
+        printf("\n");
+}
+
+static inline void swap(int *a, int *b)
+{
+    int t = *a;
+    *a = *b;
+    *b = t;
+}
+
+static void quick_sort(int *nums, int lo, int hi)
+{
+    int i, j, mid, pivot;
+
+    if (lo >= hi) {
+        return;
+    }
+
+    /* shuffle the pivot */
+    mid = lo + (hi - lo) / 2;
+    swap(&nums[mid], &nums[hi]);
+
+    i = lo - 1;
+    j = hi;
+    pivot = nums[hi];
+    while (i < j) {
+        /* For case of large amounts of consecutive duplicate elements, we
+         * shall make the partition in the middle of the array as far as
+         * possible. If the partition is located in the head or tail, the
+         * performance might well be very bad for it.
+         */
+        while (i < hi && nums[++i] < pivot) {}
+        while (j > lo && nums[--j] > pivot) {}
+        if (i < j) {
+        swap(&nums[i], &nums[j]);
+        }
+    }
+
+    /* Loop invariant: i == j + 1 or i == j */
+    swap(&nums[i], &nums[hi]);
+    quick_sort(nums, lo, i - 1);
+    quick_sort(nums, i + 1, hi);
+}
+
+int main(int argc, char **argv)
+{
+    int i, count = argc - 1;
+    int *nums = malloc(count * sizeof(int));
+    for (i = 0; i < count; i++) {
+        nums[i] = atoi(argv[i + 1]);
+    }
+
+    quick_sort(nums, 0, count - 1);
+    show(nums, 0, count - 1);
+
+    return 0;
+}