simple list application

1670-231128-pass/main.cpp

@@ -0,0 +1,143 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+class FrontMiddleBackQueue {
+public:
+    struct node{
+        node* pre;
+        node* nxt;
+        int val;
+    };
+
+    class li{
+        public:
+        node * header;
+        node * tail;
+        int sum;
+        li(){
+            header = new node();
+            tail = new node();
+            header -> nxt = tail;
+            tail->pre = header;
+            header -> val = -1;
+            tail -> val = -1;
+            sum = 0;
+        }
+        void add_node(node * previous, node * nxt, node * wait_insert){
+            wait_insert -> pre = previous;
+            wait_insert -> nxt = nxt;
+            previous->nxt = wait_insert;
+            nxt->pre = wait_insert;
+            sum++;
+        }
+        void add_front(node * x){
+            // x -> pre = header;
+            // x -> nxt = header->nxt;
+            // header->nxt->pre = x;
+            // header->nxt = x;
+            add_node(header,header->nxt,x);
+        }
+
+        void add_back(node * x){
+            // x -> nxt = tail;
+            // x -> pre = tail -> pre;
+            // tail -> pre -> nxt = x;
+            // tail -> pre = x;
+            add_node(tail->pre,tail,x);
+        }
+
+        void add_middle(node *x){
+            int cnt = sum / 2;
+            node * cur = header;
+            while(cnt){
+                cur = cur->nxt;
+                cnt--;
+            }
+            add_node(cur,cur->nxt,x);
+        }
+        void traverse(){
+            node * cur = header;
+            while(cur != tail){
+                cur = cur->nxt;
+                cout<<cur->val<<endl;
+            }
+        }
+        void retranverse(){
+            node *cur = tail;
+            while(cur!=header){
+                cur = cur->pre;
+                cout<<cur->val<<endl;
+            }
+        }
+        int del_node(int idx){
+            if(idx > sum || idx == 0) return -1;
+            int cnt = idx;
+            node * cur = header;
+            // cout<<cnt<<endl;
+            while(cnt){
+                cur = cur->nxt;
+                cnt--;
+            }
+            cur -> pre -> nxt = cur -> nxt;
+            cur -> nxt -> pre = cur -> pre;
+            int val = cur->val;
+            delete(cur);
+            sum--;
+            return val;
+        }
+    };
+    li *que;
+    FrontMiddleBackQueue() {
+        que = new li();
+    }
+    
+    void pushFront(int val) {
+        node *tmp = new node();
+        tmp->val = val;
+        que->add_front(tmp);
+    }
+    
+    void pushMiddle(int val) {
+        node * tmp = new node();
+        tmp -> val = val;
+        que->add_middle(tmp);
+    }
+    
+    void pushBack(int val) {
+       node *tmp = new node();
+       tmp -> val = val; 
+       que -> add_back(tmp);
+    }
+    
+    int popFront() {
+        return que->del_node(1);
+    }
+    
+    int popMiddle() {
+        if(que->sum % 2 == 1)
+            return que->del_node((que->sum) / 2 + 1);
+        else
+            return que->del_node((que->sum) / 2);
+    }
+    
+    int popBack() {
+        return que->del_node(que->sum);
+    }
+};
+
+int main(){
+    FrontMiddleBackQueue * q = new FrontMiddleBackQueue();
+    q->pushFront(1);
+    q->pushBack(2);
+    q->pushMiddle(3);
+    q->pushMiddle(4);
+    // q->que->traverse();
+    // q->que->retranverse();
+    cout<<q->popFront()<<endl;
+    cout<<q->popMiddle()<<endl;
+    cout<<q->popMiddle()<<endl;
+    cout<<q->popBack()<<endl;
+    cout<<q->popFront()<<endl;
+
+    return 0;
+}