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SlidingWindowMaximum.java
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SlidingWindowMaximum.java
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package com.aman.data_structures;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Stack;
public class SlidingWindowMaximum {
public static void main(String[] args) {
int[] arr = {44, 77, 33, 44, 88, 11};
System.out.println(maxSlidingWindow(arr, 3));
}
public static int[] nextGreaterElement(int[] arr){
int[] result = new int[arr.length];
Stack<Integer> stack = new Stack<>();
for(int i = arr.length - 1; i >= 0; i--){
if(!stack.isEmpty()){
while(!stack.isEmpty() && arr[stack.peek()] <= arr[i]){
stack.pop();
}
}
if(stack.isEmpty()){
result[i] = arr.length;
}
else{
result[i] = stack.peek();
}
stack.push(i);
}
return result;
}
public static List<Integer> maxSlidingWindow(int[] arr, int k){
int[] ngeArr = nextGreaterElement(arr);
List<Integer> result = new ArrayList<>();
for(int i = 0; i <= arr.length - k; i++){
int j = i;
while(ngeArr[j] < i + k){
j = ngeArr[j];
}
result.add(arr[j]);
}
return result;
}
}