修改目录结构，优化CMakeLists

src/268.c

@@ -0,0 +1,39 @@
+#include <leetcode/utils.h>
+
+#include <assert.h>
+
+int cmp(const void *a, const void *b)
+{
+    return *(const int *)a - *(const int *)b;
+}
+
+int missingNumber(int *nums, int numsSize)
+{
+    qsort(nums, numsSize, sizeof(int), cmp);
+
+    if (nums[0] != 0)
+        return 0;
+
+    for (int i = 1; i < numsSize; i++)
+    {
+        if (nums[i] - nums[i - 1] != 1)
+            return nums[i] - 1;
+    }
+
+    return nums[numsSize - 1] + 1;
+}
+
+int main()
+{
+    int num[] = {3, 0, 1};
+
+    ASSERT(missingNumber(num, sizeof(num) / sizeof(int)), 2, fail);
+
+    int num2[] = {0, 1};
+    ASSERT(missingNumber(num2, sizeof(num2) / sizeof(int)), 2, fail);
+
+    return 0;
+
+fail:
+    return -1;
+}