g2401_2500.s2454_next_greater_element_iv.Solution Maven / Gradle / Ivy

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Java-based LeetCode algorithm problem solutions, regularly updated

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package g2401_2500.s2454_next_greater_element_iv;

// #Hard #Array #Sorting #Binary_Search #Stack #Heap_Priority_Queue #Monotonic_Stack
// #2022_12_15_Time_29_ms_(95.84%)_Space_57.4_MB_(93.32%)

import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Deque;

public class Solution {
    public int[] secondGreaterElement(int[] nums) {
        int[] res = new int[nums.length];
        Arrays.fill(res, -1);
        Deque stack1 = new ArrayDeque<>();
        Deque stack2 = new ArrayDeque<>();
        Deque tmp = new ArrayDeque<>();
        for (int i = 0; i < nums.length; i++) {
            while (!stack2.isEmpty() && nums[i] > nums[stack2.peek()]) {
                res[stack2.pop()] = nums[i];
            }
            while (!stack1.isEmpty() && nums[i] > nums[stack1.peek()]) {
                tmp.push(stack1.pop());
            }
            while (!tmp.isEmpty()) {
                stack2.push(tmp.pop());
            }
            stack1.push(i);
        }
        return res;
    }
}