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int** ans;
int* ansColSize;
int ansSize;

int* t;
int tSize;

void dfs(int cur, int* nums, int numsSize) {
    
    if (cur == numsSize) {
    
        int* tmp = malloc(sizeof(int) * tSize);
        memcpy(tmp, t, sizeof(int) * tSize);
        ansColSize[ansSize] = tSize;
        ans[ansSize++] = tmp;
        return;
    }
    t[tSize++] = nums[cur];
    dfs(cur + 1, nums, numsSize);
    tSize--;
    dfs(cur + 1, nums, numsSize);
}

int** subsets(int* nums, int numsSize, int* returnSize, int** returnColumnSizes) {
    
    ans = malloc(sizeof(int*) * (1 << numsSize));
    ansColSize = malloc(sizeof(int) * (1 << numsSize));
    t = malloc(sizeof(int) * numsSize);
    *returnSize = 1 << numsSize;
    ansSize = tSize = 0;
    dfs(0, nums, numsSize);
    *returnColumnSizes = ansColSize;
    return ans;
}