题目：

题解：

int* findDisappearedNumbers(int* nums, int numsSize, int* returnSize) {
    for (int i = 0; i < numsSize; i++) {
        int x = (nums[i] - 1) % numsSize;
        nums[x] += numsSize;
    }
    int* ret = malloc(sizeof(int) * numsSize);
    *returnSize = 0;
    for (int i = 0; i < numsSize; i++) {
        if (nums[i] <= numsSize) {
            ret[(*returnSize)++] = i + 1;
        }
    }
    return ret;
}