[英]Users dissapear when I sort a doubly-linked list using quicksort
我有一個雙向鏈接的列表,我想按用戶的ELO對其排序。
問題在於,當調用函數swap()時,某些用戶會消失
這是我在控制台中得到的: https : //imgur.com/a/pJSPSnW
如您所見,第一次交換(玩家1和2之間)正確完成。 但是,當它交換玩家3和4時,user1消失了。
我認為問題出在函數swap()內,但我無法弄清楚確切的位置
代碼:用戶/節點聲明
struct user {
public:
string username;
float ELO = NULL; //Score of the user
user* next = nullptr;
user* previous = nullptr;
};
QuickSortRecursive函數
void ELOManager::_quickSortRecursive(user* low, user* high) {
if (high != nullptr && low != high && low != nullptr) {
user* p = partition(low, high);
_quickSortRecursive(low, p->previous);
_quickSortRecursive(p->next, high);
}
}
快速排序功能
void ELOManager::quickSort(){
_quickSortRecursive(first, last);
}
分區功能
user* ELOManager::partition(user* low, user* high) {
float pivot = high->ELO;
user* i = low->previous;
for (user* j = low; j != high && j!=nullptr; j = j->next) {
if (j->ELO <= pivot){
i = (i == NULL) ? low : i->next;
swap(i, j);
}
}
//i = (i == NULL) ? low : i->next;
swap(i->next, high);
cout << endl << "Loop finished -----------------------" << endl;
printUsers();
return i;
}
交換功能
void ELOManager::swap(user* A, user* B) {
user* tmp = new user();
user* swapperVector[4];
cout << endl << "swap1[" << A->username << "]" << endl;
cout << "swap2[" << B->username << "]" << endl;
if (A == B) {
cout << "Same Users: Continue" << endl;
return;
}
swapperVector[0] = A->previous;
swapperVector[1] = B->previous;
swapperVector[2] = A->next;
swapperVector[3] = B->next;
if (areTheyNeighbours(A, B)) {
A->previous->next = B;
A->next->previous = B;
B->previous->next = A;
B->next->previous = A;
A->previous = B;
B->previous = swapperVector[1];
A->next = swapperVector[3];
B->next = A;
cout << endl << "Option 1" << endl;
}
else {
A->previous = swapperVector[1];
B->previous = swapperVector[0];
A->next = swapperVector[3];
B->next = swapperVector[2];
A->previous->next = B;
A->next->previous = B;
B->previous->next = A;
B->next->previous = A;
cout << endl << "Option 2" << endl;
}
cout <<"Print list after swap" << endl << "-----" << endl;
printUsers();
}
隨意進入我項目的github https://github.com/pablogalve/ELO-System
謝謝您的幫助:)
Amanda的答案顯示了一種處理相鄰節點的方法,但是並不需要特殊情況來處理相鄰節點與非相鄰節點,如果先通過交換指向兩個目標節點的內容來完成交換,然后再進行交換兩個目標節點中的指針。
AP = A->previous;
BP = B->previous;
AN = A->next;
BN = B->next;
std::swap(AN->previous, BN->previous);
std::swap(AP->next, BP->next);
std::swap(A->previous, B->previous);
std::swap(A->next, B->next);
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.