Skip to content

Commit be66332

Browse files
krotnamekrotname
committed
Deque
1 parent 96a27e5 commit be66332

1 file changed

Lines changed: 345 additions & 0 deletions

File tree

‎src/main/java/algorithms/sprint2/Deque.java‎

Lines changed: 345 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,345 @@
1+
import java.io.ByteArrayInputStream;
2+
import java.io.ByteArrayOutputStream;
3+
import java.io.EOFException;
4+
import java.io.IOException;
5+
import java.io.InputStream;
6+
import java.io.OutputStream;
7+
8+
public class Deque {
9+
10+
// -------------------- FAST INPUT --------------------
11+
static final class FastIn {
12+
private final InputStream in;
13+
private final byte[] buf = new byte[1 << 16];
14+
private int ptr = 0, len = 0;
15+
16+
FastIn(InputStream in) {
17+
this.in = in;
18+
}
19+
20+
private int read() throws IOException {
21+
if (ptr >= len) {
22+
len = in.read(buf);
23+
ptr = 0;
24+
if (len <= 0) {
25+
return -1;
26+
}
27+
}
28+
return buf[ptr++];
29+
}
30+
31+
int nextInt() throws IOException {
32+
int c;
33+
do {
34+
c = read();
35+
if (c == -1) {
36+
throw new EOFException("Unexpected EOF");
37+
}
38+
} while (c <= ' ');
39+
40+
int sign = 1;
41+
if (c == '-') {
42+
sign = -1;
43+
c = read();
44+
}
45+
46+
int val = 0;
47+
while (c > ' ') {
48+
val = val * 10 + (c - '0');
49+
c = read();
50+
}
51+
return val * sign;
52+
}
53+
54+
String next() throws IOException {
55+
int c;
56+
do {
57+
c = read();
58+
if (c == -1) {
59+
throw new EOFException("Unexpected EOF");
60+
}
61+
} while (c <= ' ');
62+
63+
byte[] tmp = new byte[32];
64+
int n = 0;
65+
while (c > ' ') {
66+
if (n == tmp.length) {
67+
byte[] t2 = new byte[tmp.length * 2];
68+
System.arraycopy(tmp, 0, t2, 0, tmp.length);
69+
tmp = t2;
70+
}
71+
tmp[n++] = (byte) c;
72+
c = read();
73+
if (c == -1) {
74+
break;
75+
}
76+
}
77+
return new String(tmp, 0, n);
78+
}
79+
}
80+
81+
// -------------------- FAST OUTPUT --------------------
82+
static final class FastOut {
83+
private final OutputStream out;
84+
private final byte[] buf = new byte[1 << 16];
85+
private int p = 0;
86+
private final byte[] tmp = new byte[12];
87+
88+
FastOut(OutputStream out) {
89+
this.out = out;
90+
}
91+
92+
void writeByte(int b) throws IOException {
93+
if (p == buf.length) {
94+
flush();
95+
}
96+
buf[p++] = (byte) b;
97+
}
98+
99+
void writeStr(String s) throws IOException {
100+
for (int i = 0; i < s.length(); i++) {
101+
writeByte(s.charAt(i));
102+
}
103+
}
104+
105+
void writeInt(int x) throws IOException {
106+
if (x == 0) {
107+
writeByte('0');
108+
return;
109+
}
110+
if (x < 0) {
111+
writeByte('-');
112+
x = -x;
113+
}
114+
115+
int k = 0;
116+
while (x > 0) {
117+
tmp[k++] = (byte) ('0' + (x % 10));
118+
x /= 10;
119+
}
120+
for (int i = k - 1; i >= 0; i--) {
121+
writeByte(tmp[i]);
122+
}
123+
}
124+
125+
void flush() throws IOException {
126+
out.write(buf, 0, p);
127+
p = 0;
128+
}
129+
}
130+
131+
// -------------------- RING BUFFER DEQUE --------------------
132+
static final class RingDeque {
133+
private final int[] a;
134+
private final int cap;
135+
private int head = 0; // индекс первого элемента
136+
private int tail = 0; // индекс позиции "после последнего"
137+
private int size = 0;
138+
139+
RingDeque(int cap) {
140+
this.cap = cap;
141+
this.a = new int[cap];
142+
}
143+
144+
private int next(int i) {
145+
i++;
146+
if (i == cap) {
147+
i = 0;
148+
}
149+
return i;
150+
}
151+
152+
private int prev(int i) {
153+
i--;
154+
if (i == -1) {
155+
i = cap - 1;
156+
}
157+
return i;
158+
}
159+
160+
boolean isEmpty() {
161+
return size == 0;
162+
}
163+
164+
boolean isFull() {
165+
return size == cap;
166+
}
167+
168+
void pushBack(int x) {
169+
a[tail] = x;
170+
tail = next(tail);
171+
size++;
172+
}
173+
174+
void pushFront(int x) {
175+
head = prev(head);
176+
a[head] = x;
177+
size++;
178+
}
179+
180+
int popFront() {
181+
int x = a[head];
182+
head = next(head);
183+
size--;
184+
return x;
185+
}
186+
187+
int popBack() {
188+
tail = prev(tail);
189+
int x = a[tail];
190+
size--;
191+
return x;
192+
}
193+
}
194+
195+
private static void process(FastIn in, FastOut out) throws Exception {
196+
int n = in.nextInt();
197+
int m = in.nextInt();
198+
199+
RingDeque dq = new RingDeque(m);
200+
201+
for (int i = 0; i < n; i++) {
202+
String cmd = in.next();
203+
204+
if ("push_back".equals(cmd)) {
205+
int x = in.nextInt();
206+
if (dq.isFull()) {
207+
out.writeStr("error\n");
208+
} else {
209+
dq.pushBack(x);
210+
}
211+
} else if ("push_front".equals(cmd)) {
212+
int x = in.nextInt();
213+
if (dq.isFull()) {
214+
out.writeStr("error\n");
215+
} else {
216+
dq.pushFront(x);
217+
}
218+
} else if ("pop_front".equals(cmd)) {
219+
if (dq.isEmpty()) {
220+
out.writeStr("error\n");
221+
} else {
222+
out.writeInt(dq.popFront());
223+
out.writeByte('\n');
224+
}
225+
} else { // pop_back
226+
if (dq.isEmpty()) {
227+
out.writeStr("error\n");
228+
} else {
229+
out.writeInt(dq.popBack());
230+
out.writeByte('\n');
231+
}
232+
}
233+
}
234+
}
235+
236+
private static void run() throws Exception {
237+
FastIn in = new FastIn(System.in);
238+
FastOut out = new FastOut(System.out);
239+
process(in, out);
240+
out.flush();
241+
}
242+
243+
// -------------------- TESTS --------------------
244+
private static String solveIO(String input) throws Exception {
245+
ByteArrayInputStream bin = new ByteArrayInputStream(input.getBytes());
246+
ByteArrayOutputStream bout = new ByteArrayOutputStream();
247+
FastIn in = new FastIn(bin);
248+
FastOut out = new FastOut(bout);
249+
process(in, out);
250+
out.flush();
251+
return bout.toString();
252+
}
253+
254+
private static void test() throws Exception {
255+
// Пример 1
256+
assertEq(
257+
"861\n-819\n",
258+
solveIO(
259+
"4\n" +
260+
"4\n" +
261+
"push_front 861\n" +
262+
"push_front -819\n" +
263+
"pop_back\n" +
264+
"pop_back\n"
265+
)
266+
);
267+
268+
// Пример 2
269+
assertEq(
270+
"-855\n0\n844\n",
271+
solveIO(
272+
"7\n" +
273+
"10\n" +
274+
"push_front -855\n" +
275+
"push_front 0\n" +
276+
"pop_back\n" +
277+
"pop_back\n" +
278+
"push_back 844\n" +
279+
"pop_back\n" +
280+
"push_back 823\n"
281+
)
282+
);
283+
284+
// Пример 3
285+
assertEq(
286+
"20\n102\n",
287+
solveIO(
288+
"6\n" +
289+
"6\n" +
290+
"push_front -201\n" +
291+
"push_back 959\n" +
292+
"push_back 102\n" +
293+
"push_front 20\n" +
294+
"pop_front\n" +
295+
"pop_back\n"
296+
)
297+
);
298+
299+
// Емкость 1 + переполнение
300+
assertEq(
301+
"error\n1\nerror\n",
302+
solveIO(
303+
"4\n" +
304+
"1\n" +
305+
"push_front 1\n" +
306+
"push_back 2\n" +
307+
"pop_back\n" +
308+
"pop_front\n"
309+
)
310+
);
311+
312+
// Проверка кольцевого перехода (wrap-around)
313+
assertEq(
314+
"1\n4\n2\n3\n",
315+
solveIO(
316+
"8\n" +
317+
"3\n" +
318+
"push_back 1\n" +
319+
"push_back 2\n" +
320+
"push_back 3\n" +
321+
"pop_front\n" +
322+
"push_back 4\n" +
323+
"pop_back\n" +
324+
"pop_front\n" +
325+
"pop_front\n"
326+
)
327+
);
328+
329+
System.out.println("Test OK");
330+
}
331+
332+
static void assertEq(String exp, String act) {
333+
if (!exp.equals(act)) {
334+
throw new AssertionError("Expected:\n" + exp + "\nActual:\n" + act);
335+
}
336+
}
337+
338+
public static void main(String[] args) throws Exception {
339+
if (System.getProperty("os.name").startsWith("Windows")) {
340+
test();
341+
} else {
342+
run();
343+
}
344+
}
345+
}

0 commit comments

Comments
 (0)