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  1. #include <cstdio>
  2. #include <cstdlib>
  3. #include <cmath>
  4. #include <cassert>
  5. #include <iostream>
  6.  
  7. struct listNode{
  8.   int data;
  9.   struct listNode *nextptr;
  10. };
  11.  
  12. typedef struct listNode ListNode;
  13. typedef ListNode *ListNodePtr;
  14.  
  15. ListNodePtr create(const int W) { 
  16.   assert(W >= 1            && "What are you thinking ?");
  17.   ListNodePtr headPtr = (ListNodePtr)malloc(sizeof(ListNode));
  18.   headPtr->data    = 0;
  19.   headPtr->nextptr = NULL;
  20.   ListNodePtr lastPtr = headPtr;
  21.   for(int i=1;i<W;i++){
  22.     ListNodePtr nowPtr = (ListNodePtr)malloc(sizeof(ListNode));
  23.     nowPtr->data=i;
  24.     nowPtr->nextptr=NULL; 
  25.     lastPtr->nextptr=nowPtr;
  26.         lastPtr=nowPtr;
  27.   }
  28.   return headPtr;
  29. };
  30.  
  31. int ranX(ListNodePtr *headPtrPtr, const int W){
  32.   assert(headPtrPtr != NULL && "Are you kidding me ?");
  33.   assert(W >= 1             && "What are you thinking ?");
  34.   ListNodePtr headPtr = *headPtrPtr;
  35.   assert(headPtr != NULL    && "You want too much.");
  36.   int r=rand()%W;
  37.   ListNodePtr lastPtr = NULL;
  38.   ListNodePtr nowPtr  = headPtr;
  39.   for(int i=0; i<r && nowPtr->nextptr !=NULL;i++){
  40.     lastPtr=nowPtr;
  41.     nowPtr=nowPtr->nextptr;
  42.   }
  43.   int data = nowPtr->data;
  44.   if (lastPtr == NULL) {
  45.     *headPtrPtr = NULL;
  46.   } else {
  47.     lastPtr->nextptr = nowPtr->nextptr;
  48.   }
  49.         free(nowPtr);
  50.   return data;
  51. };
  52.  
  53. int main() {
  54.   const int W = 10;
  55.   ListNodePtr headPtr = create(W);
  56.   for (int i = 0; i < W+1; ++i) {
  57.     std::cout << ranX(&headPtr, W) << std::endl;
  58.   }
  59.   return 0;
  60. }
  61.  
Runtime error #stdin #stdout #stderr 0s 3432KB
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Standard input is empty
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prog: prog.cpp:35: int ranX(ListNode**, int): Assertion `headPtr != __null && "You want too much."' failed.
https://ideone.com/58xey0
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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