51 lines
1.1 KiB
Java
51 lines
1.1 KiB
Java
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import java.util.*;
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public class QueueMin<E extends Comparable<E>> {
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List<E[]> s1 = new ArrayList<>();
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List<E[]> s2 = new ArrayList<>();
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E min(E a, E b) {
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return a.compareTo(b) < 0 ? a : b;
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}
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public E min() {
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if (s1.isEmpty())
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return s2.get(s2.size() - 1)[1];
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if (s2.isEmpty())
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return s1.get(s1.size() - 1)[1];
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return min(s1.get(s1.size() - 1)[1], s2.get(s2.size() - 1)[1]);
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}
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public void addLast(E x) {
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E minima = x;
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if (!s1.isEmpty()) {
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minima = min(minima, s1.get(s1.size() - 1)[1]);
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}
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s1.add((E[]) new Comparable[]{x, minima});
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}
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public E removeFirst() {
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if (s2.isEmpty()) {
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E minima = null;
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while (!s1.isEmpty()) {
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E x = s1.remove(s1.size() - 1)[0];
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minima = minima == null ? x : min(minima, x);
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s2.add((E[]) new Comparable[]{x, minima});
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}
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}
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return s2.remove(s2.size() - 1)[0];
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}
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// Usage example
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public static void main(String[] args) {
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QueueMin<Integer> q = new QueueMin<>();
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q.addLast(2);
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q.addLast(3);
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System.out.println(2 == q.min());
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q.removeFirst();
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System.out.println(3 == q.min());
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q.addLast(1);
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System.out.println(1 == q.min());
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}
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}
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