Maximum in a sliding window - c++

Question

i am unable to detect why i am getting wrong answer in the problem subarrays given on spoj .The problem is to determine the maximum element in k sized window .
i have applied sliding window algorithm which uses deque and maintains the index of the maximum element always at the front.
here is my code :
#include<iostream>
#include<deque>
using namespace std;
int main()
{
int n;
cin>>n;
int arr[n];
for(int i=0;i<n;i++)
{
cin>>arr[i];
}
int k;
cin>>k;
deque<int>q;
int ans[n-k+1];
for(int i=0;i<k;i++)
{
while(!q.empty()&&arr[i]>=arr[q.back()])
q.pop_back();
q.push_back(i);
}
for(int i=k;i<n;i++)
{
ans[i-k]=arr[q.front()];
while(!q.empty()&&arr[i]>=arr[q.back()])
q.pop_back();
while(!q.empty()&&q.front()<=i-k)
q.pop_front();
q.push_back(i);
}
ans[n-k]=arr[q.front()];
for(int i=0;i<=n-k;i++)
{
cout<<ans[i];
}
cout<<"\n";
return 0;
}

Answer 1

Simple C++ logic would be...
#include <iostream>
#include<stdio.h>
int main() {
int temp;
int A[] = {1,2,-1,7,8,-3,-4};
int max = A[0];
printf("%d\n",max);
int n = 7;
for(int i = 1 ; i <= n; i++)
{
for(int j = 0; j <= n-i ; j++)
{
temp = 0;
for(int k = 0; k < i; k++)
{
temp+=A[j+k];
}
if(temp > max)
max = temp;
//printf("%d\n",max);
}
}
printf("%d\n",max);
return 0;
}

Answer 2

You can do it using a simple array. I am writing the Java solution which you can change into your preferred language.
public class SlidingWindowMaximum {
public static void main(String[] args) {
int[] arr={1,3,-1,-3,5,3,6, 7};
int winSize=3;
int[] arrMax=getMax(arr,winSize);
display(arrMax);
}
// This method gives you the array of the mx value for SlidingWindow problem.
private static int[] getMax(int[] A,int B){
List<Integer> list=new ArrayList<>();
int[] tempA=new int[B];
for(int i=0;i<A.length-B+1;i++){
int tempi=0;
for(int j=i;j<i+B;j++){
tempA[tempi]=A[j];
tempi++;
}
int retMax=getMaxValueFromSortedArray(tempA);
list.add(retMax);
}
int[] array = list.stream().mapToInt(i->i).toArray();
return array;
}
// This method gives you the maxValue from the window of size required.
private static int getMaxValueFromSortedArray(int[] tempA){
int maxValue=0;
for(int j=0;j<tempA.length;j++){
Arrays.sort(tempA);
maxValue=tempA[tempA.length-1];
}
return maxValue;
}
// Display metod to print array elements.
private static void display(int[] arr){
for (int i=0;i<arr.length;i++){
System.out.print(" "+arr[i]);
}
System.out.println("");
}
}