1. 数组模拟单链表
题目：www.acwing.com/problem/con…
public class num826 {
private static int N = 100010;
private static int head;
private static int[] e = new int[N];
private static int[] ne = new int[N];
private static int idx;
private static void init() {
head = -1;
idx = 0;
}
private static void addHead(int x) {
ne[idx] = head;
head = idx;
e[idx++] = x;
}
private static void addElement(int k, int x) {
e[idx] = x;
ne[idx] = ne[k - 1];
ne[k - 1] = idx;
++idx;
}
private static void delete(int k) {
if (k == 0) {
head = ne[head];
} else {
ne[k - 1] = ne[ne[k - 1]];
}
}
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
int m = Integer.parseInt(reader.readLine());
init();
while (m-- > 0) {
String[] s = reader.readLine().split(" ");
int k = Integer.parseInt(s[1]);
if (s[0].equals("H")) {
addHead(k);
} else if (s[0].equals("I")) {
int x = Integer.parseInt(s[2]);
addElement(k, x);
} else {
delete(k);
}
}
for (int i = head; i != -1; i = ne[i]) {
System.out.print(e[i] + " ");
}
}
}
2. 数组模拟双链表
题目：www.acwing.com/problem/con…
public class num827 {
private static int N = 100010;
private static int head;
private static int tail;
private static int idx;
private static int[] e = new int[N];
private static int[] l = new int[N];
private static int[] r = new int[N];
public static void init() {
head = -1;
tail = -1;
idx = 0;
}
public static void addRight(int x) {
e[idx] = x;
if (tail == -1) {
head = tail = idx;
r[idx] = -1;
l[idx] = -1;
} else {
r[tail] = idx;
l[idx] = tail;
r[idx] = -1;
tail = idx;
}
++idx;
}
public static void addLeft(int x) {
e[idx] = x;
if (head == -1) {
head = tail = idx;
r[idx] = -1;
l[idx] = -1;
} else {
l[head] = idx;
r[idx] = head;
l[idx] = -1;
head = idx;
}
++idx;
}
public static void addIRight(int k, int x) {
e[idx] = x;
if (r[k] != -1) {
l[r[k]] = idx;
}
r[idx] = r[k];
r[k] = idx;
l[idx] = k;
if (r[idx] == -1) {
tail = idx;
}
++idx;
}
public static void addILeft(int k, int x) {
e[idx] = x;
if (l[k] != -1) {
r[l[k]] = idx;
}
l[idx] = l[k];
l[k] = idx;
r[idx] = k;
if (l[idx] == -1) {
head = idx;
}
++idx;
}
public static void delete(int k) {
if (head == k) {
head = r[k];
if (head == -1) {
tail = -1;
return;
}
l[r[k]] = -1;
} else if (tail == k) {
tail = l[k];
if (tail == -1) {
head = -1;
return;
}
r[l[k]] = -1;
} else {
r[l[k]] = r[k];
l[r[k]] = l[k];
}
}
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
int m = Integer.parseInt(reader.readLine());
init();
while (m-- > 0) {
String[] s = reader.readLine().split(" ");
int k = Integer.parseInt(s[1]);
switch (s[0]) {
case "R":
addRight(k);
break;
case "L":
addLeft(k);
break;
case "D":
delete(k - 1);
break;
case "IL": {
int x = Integer.parseInt(s[2]);
addILeft(k - 1, x);
break;
}
default: {
int x = Integer.parseInt(s[2]);
addIRight(k - 1, x);
break;
}
}
}
for (int i = head; i != -1; i = r[i]) {
System.out.print(e[i] + " ");
}
}
}
3. 数组模拟栈
题目：www.acwing.com/problem/con…
public class num828 {
private static int N = 100010;
private static int[] stack = new int[N];
private static int head;
private static void init() {
head = -1;
}
private static void push(int x) {
++head;
stack[head] = x;
}
private static int query() {
return stack[head];
}
private static boolean empty() {
return head == -1;
}
private static int pop() {
return stack[head--];
}
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
int m = Integer.parseInt(reader.readLine());
init();
while (m-- > 0) {
String[] s = reader.readLine().split(" ");
switch (s[0]) {
case "push":
push(Integer.parseInt(s[1]));
break;
case "query":
System.out.println(query());
break;
case "empty":
System.out.println(empty() ? "YES" : "NO");
break;
default:
pop();
}
}
}
}
4. 数组模拟队列
题目：www.acwing.com/problem/con…
public class num829 {
private static int N = 100010;
private static int[] queue = new int[N];
private static int head;
private static int tail;
private static void init() {
head = 0;
tail = 0;
}
private static void push(int x) {
queue[tail++] = x;
}
private static int query() {
return queue[head];
}
private static boolean empty() {
return head == tail;
}
private static int pop() {
return queue[head++];
}
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
int m = Integer.parseInt(reader.readLine());
init();
while (m-- > 0) {
String[] s = reader.readLine().split(" ");
switch (s[0]) {
case "push":
push(Integer.parseInt(s[1]));
break;
case "query":
System.out.println(query());
break;
case "empty":
System.out.println(empty() ? "YES" : "NO");
break;
default:
pop();
}
}
}
}
