43 lines
1.3 KiB
Java
43 lines
1.3 KiB
Java
// Author: Rodney Shaghoulian
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// Github: github.com/RodneyShag
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// HackerRank: hackerrank.com/RodneyShag
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import java.util.Scanner;
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import java.util.Stack;
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// All 3 queries (1:push, 2:delete, 3:print max) are all O(1) runtime
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public class Solution {
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public static void main(String[] args) {
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Stack<Integer> stack = new Stack<Integer>();
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Stack<Integer> maxStack = new Stack<Integer>(); // keeps track of maximums
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Scanner scan = new Scanner(System.in);
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int N = scan.nextInt();
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for (int i = 0; i < N; i++) {
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int query = scan.nextInt();
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switch (query) {
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case 1:
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int x = scan.nextInt();
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stack.push(x);
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if (maxStack.isEmpty() || x >= maxStack.peek()) {
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maxStack.push(x);
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}
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break;
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case 2:
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int poppedValue = stack.pop();
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if (poppedValue == maxStack.peek()) {
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maxStack.pop();
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}
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break;
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case 3:
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System.out.println(maxStack.peek());
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break;
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default:
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break;
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}
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}
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scan.close();
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}
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}
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