Rotate array

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

Author: begeekmyfriend

189_rotate_array/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test rotate_array.c

189_rotate_array/rotate_array.c

@@ -0,0 +1,49 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+static void reverse(int *nums, int lo, int hi)
+{
+    while (lo < hi) {
+        int tmp = nums[lo];
+        nums[lo] = nums[hi];
+        nums[hi] = tmp;
+        lo++;
+        hi--;
+    }
+}
+
+static void rotate(int* nums, int numsSize, int k)
+{
+    k %= numsSize;
+    if (k == 0) {
+        return;
+    }
+
+    reverse(nums, 0, numsSize - 1 - k);
+    reverse(nums, numsSize - k, numsSize - 1);
+    reverse(nums, 0, numsSize - 1);
+}
+
+int main(int argc, char **argv)
+{
+    if (argc < 2) {
+        fprintf(stderr, "Usage: ./test k n1 n2...\n");
+        exit(-1);
+    }
+
+    int k = atoi(argv[1]);
+    int i, count = argc - 2;
+    int *nums = malloc(count * sizeof(int));
+    for (i = 0; i < count; i++) {
+        nums[i] = atoi(argv[i + 2]);
+    }
+
+    rotate(nums, count, k);
+
+    for (i = 0; i < count; i++) {
+        printf("%d ", nums[i]);
+    }
+    printf("\n");
+
+    return 0;
+}