leetcode - Copy List with Random Pointer

 

/**
 * Definition for singly-linked list with a random pointer.
 * struct RandomListNode {
 *     int label;
 *     RandomListNode *next, *random;
 *     RandomListNode(int x) : label(x), next(NULL), random(NULL) {}
 * };
 */

/*struct NodeInfo{
    RandomListNode * node;
    int pos;
    NodeInfo(RandomListNode * n, int p):node(n),pos(p){}
};

bool compare(NodeInfo a, NodeInfo b){
    return a.node - b.node < 0;
}
*/
class Solution {
public:
    RandomListNode *copyRandomList(RandomListNode *head) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        //vector<NodeInfo> infos;
        map<unsigned, int> infoMap;
        vector<RandomListNode*> nodes; 
        if (head== NULL)
            return head;
        int i=0;
        RandomListNode * temp = head;
        while (temp!=NULL){
            infoMap[(unsigned)temp] = i;
            nodes.push_back(new RandomListNode(temp->label));
            int sz = nodes.size();
            if (sz>1)
                nodes[sz-2]->next = nodes[sz-1];
            i++;
            temp = temp->next;
        }
        temp = head;
        i=0;
        while(temp!=NULL){
            if(temp->random==NULL)
                nodes[i]->random=NULL;
            else{
                nodes[i]->random = nodes[infoMap[(unsigned)temp->random]];
            }
            i++;
            temp = temp->next;
        }
        return nodes[0];
    }
};