力扣2. Add Two Numbers

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */


struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2){
    struct ListNode *pr=(struct ListNode*)malloc(sizeof(struct ListNode));
    struct ListNode *p1=l1,*p2=l2,*p3=pr;
    int flag=0;
    while(p1!=NULL||p2!=NULL){
        struct ListNode *t=(struct ListNode*)malloc(sizeof(struct ListNode));
        pr->next=t;
        pr=t;
        if(p1!=NULL&&p2!=NULL)
            t->val=p1->val+p2->val;
        else if(p1!=NULL)
            t->val=p1->val;
        else if(p2!=NULL)
            t->val=p2->val;
        if(flag==1){
            t->val++;
            flag=0;
        }
        if(t->val>=10){
            t->val%=10;
            flag=1;
        }
        if(p1!=NULL)
            p1=p1->next;
        if(p2!=NULL)
            p2=p2->next;
    }
    
    if(flag==1){
        struct ListNode *t=(struct ListNode*)malloc(sizeof(struct ListNode));
        t->val=1;
        pr->next=t;
        pr=t;
    }
    pr->next=NULL;
    return p3->next;
    
}