827. 双链表

https://www.acwing.com/problem/content/submission/code_detail/7412150/

AcWing/827/827.cpp

@@ -0,0 +1,39 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int m, x, k, p;
+string op;
+list<int> a;
+list<int>::iterator it[100005];
+
+int main() {
+    cin >> m;
+    while (m--) {
+        cin >> op;
+        if (op == "L") {
+            cin >> x;
+            a.push_front(x);
+            it[++p] = a.begin();
+        } else if (op == "R") {
+            cin >> x;
+            a.push_back(x);
+            it[++p] = --a.end();
+        } else if (op == "D") {
+            cin >> k;
+            a.erase(it[k]);
+        } else if (op == "IL") {
+            cin >> k >> x;
+            it[++p] = a.insert(it[k], x);
+        } else {
+            cin >> k >> x;
+            auto itk = it[k];
+            it[++p] = a.insert(++itk, x);
+        }
+    }
+    for (int i : a) {
+        cout << i << ' ';
+    }
+    cout << endl;
+    return 0;
+}