题目：

题解：

typedef struct SummaryRanges{
    int left,right;
    struct SummaryRanges *pre,*next;
} SummaryRanges;

/** Initialize your data structure here. */

SummaryRanges* summaryRangesCreate() {
    SummaryRanges *head = malloc(sizeof(SummaryRanges)),*rear = malloc(sizeof(SummaryRanges));
    head->next = head->pre = rear;
    rear->next = rear->pre = head;
    head->left = 0;
    return head;
}
SummaryRanges *insert(SummaryRanges *head,SummaryRanges *rear,int val){
    SummaryRanges *p = head->next;
    while(p != rear){
        if(p->left <= val && val <= p->right) return NULL;
        else if(p->right < val) p = p->next;
        else break;
    }
    SummaryRanges *q = malloc(sizeof(SummaryRanges));
    q->left = q->right = val;
    q->next = p,q->pre = p->pre;
    p->pre->next = q,p->pre = q;
    ++head->left;
    return q;
}
void summaryRangesAddNum(SummaryRanges* obj, int val) {
    SummaryRanges *head = obj,*rear = obj->pre;
    SummaryRanges *p = insert(head,rear,val);
    if(!p) return;
    int f1 = p->pre != head && p->pre->right+1 == p->left,f2 = p->next != rear && p->next->left-1 == p->right;
    if(f1 && f2){
        p->pre->right = p->next->right;
        p->pre->next = p->next->next;
        p->next->next->pre = p->pre;
        head->left -= 2;
        free(p->next);
        free(p);
    }
    else if(f1){
        p->pre->right = p->right;
        p->pre->next = p->next;
        p->next->pre = p->pre;
        head->left--;
        free(p);
    }
    else if(f2){
        p->next->left = p->left;
        p->next->pre = p->pre;
        p->pre->next = p->next;
        head->left--;
        free(p);
    }
}

int** summaryRangesGetIntervals(SummaryRanges* obj, int* rs, int** rcs) {
    SummaryRanges *p = obj->next,*rear = obj->pre;
    int **ret = malloc((obj->left)*sizeof(int*));
    *rs = 0;
    while(p != rear){
        ret[*rs] = malloc(2*sizeof(int));
        ret[*rs][0] = p->left,ret[*rs][1] = p->right;
        (*rs)++;
        p = p->next;
    }
    *rcs = malloc((*rs)*sizeof(int));
    for(int i = 0;i < *rs;++i) (*rcs)[i] = 2;
    return ret;
}

void summaryRangesFree(SummaryRanges* obj) {
    SummaryRanges *p = obj->next,*rear = obj->pre;
    while(p != rear){
        SummaryRanges *temp = p->next;
        free(p);
        p = temp;
    }
    free(rear);
    free(obj);
}

/**
 * Your SummaryRanges struct will be instantiated and called as such:
 * SummaryRanges* obj = summaryRangesCreate();
 * summaryRangesAddNum(obj, val);
 
 * int** param_2 = summaryRangesGetIntervals(obj, retSize, retColSize);
 
 * summaryRangesFree(obj);
*/