题目要求：
1、使用c语言实现，不能使用c++的stl容器，map、vector等等
2、自己定义数据结构
3、如果需要排序，自己写排序算法
股票交易中，高峰期委托买卖数量是十分大的，尤其在9:30分左右，而证券公司关心的抢手的信息条数会远小于委托买卖数量。实际情况是题目中的n会非常大，而s很小，因此需要考虑算法的时间复杂度。
题目如下：
京东笔试-交易清单（京东2016实习生真题）
题目描述
金融证券行业超好的薪酬待遇，吸引了大批的求职者前往应聘，小东也不例外，准备应聘一家证券公司。面试官为考察她的数据分析、处理和编码能力，为她准备了以下问题。
股票交易中，委托是指股票交易者在证券公司买卖股票。每手委托包括一个委托单号i、价格pi、买入或卖出标记di及交易数量qi。
交易处理中，需要把同类业务（买入或卖出）中相同价格的所有委托合并起来，形成一个清单。清单的第一部分为按价格降序排列的合并后的卖出委托，紧随其后的是按相同顺序排列的买入合并委托。证券公司比较关心的是比较抢手的s条合并委托信息，需要得到买入及卖出最抢手的s条合并委托。对于买入委托，抢手的是指报价高的委托，而卖出委托中报价低的较为抢手。若买或卖的合并委托数小于s条，则全部列入清单中。
现在小东拿到的是n个委托，请你帮忙找出最抢手的s个合并委托。
输入
输入有若干组，每组的第一行为两个正整数n和s（1<=n<=1000，1<=s<=50），分别表示委托数和最抢手的清单数，接下来的n行为具体的委托信息，每行包含3部分，第一部分为一个字母‘B’或‘S’，表示买入或卖出，后两部分为两个整数p和q，表示报价和数量。任何卖出委托的报价都比买入委托的报价高。
输出
输出不超过2s行合并委托清单，格式与输入相同。
样例输入
6 2
B 10 3
S 50 2
S 40 1
S 50 6
B 20 4
B 25 10
样例输出
S 40 1
S 50 8
B 25 10
B 20 4
#include<stdio.h>
#include<stdlib.h>
#include<assert.h>
#include<stdbool.h>
typedef struct {
unsigned int in;
unsigned int out;
}InOut;
typedef struct {
char type; // transaction type, 'B' means buy, 'S' means sell.
unsigned int price;
unsigned int quantity;
} TransData;
// DDL - Doubly Linked List.
typedef struct _node {
TransData data;
struct _node *next, *prev;
}DDLNode;
typedef struct _list {
DDLNode *head, *tail;
}DDL;
DDLNode* CreateDDLNode(TransData *pData);
void ShowDDLNode(DDLNode *pNode);
void InitDDL(DDL *pddl);
bool IsEmptyDDL(DDL *pList);
bool IsHeadNode(DDL *pList, DDLNode *pNode);
bool IsTailNode(DDL *pList, DDLNode *pNode);
// DDDL - Descending DDL.
int InsertToDDDL(DDL *pList, TransData *pData);
void ShowDDLFromHead(DDL *pList, unsigned int cnt);
void ShowDDLFromTail(DDL *pList, unsigned int cnt);
#define CHECK_NULL_POINTER(ptr) \
if(!ptr){ \
fprintf(stderr, "null pointer at %s, line %d\n", __FUNCTION__, __LINE__); \
exit(-1); \
}
int main(){
InOut io = {0,0};
DDL sddl, bddl;
int i;
printf("Please input transactions count (in out):");
scanf(" %u %u", &io.in, &io.out);
//printf("io(%u, %u)\n", io.in, io.out);
printf("Please input the raw transaction data.\"('B' price quantity)\" for buying stocks, \"('S' price quantity)\" for selling stocks.\n");
TransData record[io.in];
for(i = 0; i < io.in; ){
scanf(" %c %u %u", &(record[i].type), &(record[i].price), &(record[i].quantity));
//printf("record[%d]:%c, %u, %u\n", i, record[i].type, record[i].price, record[i].quantity);
if(record[i].type != 'B' && record[i].type != 'S'){
printf("Wrong transaction type. It must be 'B' or 'S'!\n");
continue;
}
else{
++i;
}
}
InitDDL(&sddl);
InitDDL(&bddl);
for(i = 0; i < io.in; ++i){
//printf("\ninsert record[%d]: %c %u %u\n", i, record[i].type, record[i].price, record[i].quantity);
if(record[i].type == 'B'){
InsertToDDDL(&bddl, &(record[i]) );
}
else if(record[i].type == 'S'){
InsertToDDDL(&sddl, &(record[i]) );
}
}
printf("\noutput:\n");
ShowDDLFromTail(&sddl, io.out);
ShowDDLFromHead(&bddl, io.out);
return 0;
}
DDLNode* CreateDDLNode(TransData *pData){
DDLNode *pNewNode = (DDLNode *)malloc(sizeof(DDLNode));
CHECK_NULL_POINTER(pNewNode);
if(pData){
pNewNode->data.type = pData->type;
pNewNode->data.price = pData->price;
pNewNode->data.quantity = pData->quantity;
}
else{
pNewNode->data.type = 0;
pNewNode->data.price = 0;
pNewNode->data.quantity = 0;
}
pNewNode->next = NULL;
pNewNode->prev = NULL;
}
void ShowDDLNode(DDLNode *pNode){
if(pNode)
printf("%c %u %u %p %p %p\n", pNode->data.type, pNode->data.price, pNode->data.quantity, pNode, pNode->prev, pNode->next);
else
printf("null node\n");
}
void InitDDL(DDL *pList){
CHECK_NULL_POINTER(pList);
pList->head = NULL;
pList->tail = NULL;
}
bool IsEmptyDDL(DDL *pList){
CHECK_NULL_POINTER(pList);
return pList->head == NULL && pList->tail == NULL;
}
bool IsHeadNode(DDL *pList, DDLNode *pNode){
CHECK_NULL_POINTER(pList);
return pList->head == pNode;
}
bool IsTailNode(DDL *pList, DDLNode *pNode){
CHECK_NULL_POINTER(pList);
return pList->tail == pNode;
}
/*Function: create a new node to save data, and insert or merge it to descending DDL.
*@return value: 0 : success, -1 : fail.
*/
int InsertToDDDL(DDL *pList, TransData *pData){
CHECK_NULL_POINTER(pList);
if(IsEmptyDDL(pList) ){
DDLNode *pNewNode = CreateDDLNode(pData);
pList->head = pNewNode;
pList->tail = pNewNode;
return 0;
}
DDLNode *pNode = pList->head;
while(pNode){
if(pNode->data.price == pData->price){
pNode->data.quantity += pData->quantity;
return 0;
}
if(pNode->data.price < pData->price){
//Insert a new node before pNode.
DDLNode *pNewNode = CreateDDLNode(pData);
if(IsHeadNode(pList, pNode) ){
pNewNode->next = pNode;
pNode->prev = pNewNode;
pList->head = pNewNode;
return 0;
}
pNewNode->prev = pNode->prev;
pNode->prev->next = pNewNode;
pNewNode->next = pNode;
pNode->prev = pNewNode;
return 0;
}
if(pNode->data.price > pData->price){
if(IsTailNode(pList, pNode) ){
//Insert a new node after pNode.
DDLNode *pNewNode = CreateDDLNode(pData);
pNode->next = pNewNode;
pNewNode->prev = pNode;
pList->tail = pNewNode;
return 0;
}
pNode = pNode->next;
}
}
fprintf(stderr, "Fail to insert node to descending DDL.");
return -1;
}
void ShowDDLFromHead(DDL *pList, unsigned int cnt){
CHECK_NULL_POINTER(pList);
unsigned int i=0;
DDLNode *pNode = pList->head;
for(; i < cnt && pNode; ++i, pNode = pNode->next){
printf("%c %u %u\n", pNode->data.type, pNode->data.price, pNode->data.quantity);
}
}
void ShowDDLFromTail(DDL *pList, unsigned int cnt){
CHECK_NULL_POINTER(pList);
unsigned int i=0;
DDLNode *pNode = pList->tail;
for(; i < cnt && pNode; ++i, pNode = pNode->prev){
printf("%c %u %u\n", pNode->data.type, pNode->data.price, pNode->data.quantity);
}
}