How do I solve the following problem ?

#include <stdio.h>
#include <math.h>
#define LL long long
 
typedef struct{
    LL val;
    int index;
}type1;
 
void merge(type1 A[], int l, int m, int r)
{
    int n1 = m - l + 1, n2 = r - m, i, j, k;
    type1 left[n1 + 1], right[n2 + 1];
 
    for(i = 1; i <= n1; i++)
        left[i] = A[l + i - 1];
 
    for(i = 1; i <= n2; i++)
        right[i] = A[m + i];
 
    left[n1 + 1].val = INFINITY;
    right[n2 + 1].val = INFINITY;
 
    i = 1;
    j = 1;
    for(k = l; k <= r; k++)
    {
        if(left[i].val <= right[j].val)
        {
            A[k] = left[i];
            i++;
        }
        else
        {
            A[k] = right[j];
            j++;
        }
 
    }
 
 
}
 
void mergesort(type1 A[], int l, int r)
{
    if(r > l)
    {
        int m = (l + r) / 2;
 
        mergesort(A, l, m);
        mergesort(A, m+1, r);
        merge(A, l, m, r);
 
    }
}
 
int main(void)
{
    int t;
    scanf("%d", &t);
 
    while(t--)
    {
       int n, i, j, k, p, q;
       scanf("%d", &n);
 
       type1 C[n];
 
       // Getting input for array C
       for(i = 1; i <= n; i++){
           scanf("%lld", &C[i].val);
           C[i].index = i;
       }
 
       mergesort(C, 1, n);
 
       // Declaring a 2D matrix for storing the links between p & q
       int arr[n+1][n+1];
 
       // Initializing arr[][] to 0
       for(i = 0; i <= n; i++)
       {
           for(j = 0; j <= n; j++){
               if(i == j)
                   arr[i][j] = 1;
               else
                   arr[i][j] = 0;
           }
       }
 
       // Getting input for our pairs of p & q and updating arr[][]
       for(i = 0; i < n-1; i++)
       {
           scanf("%d %d", &p, &q);
           arr[p][q] = 1;
           arr[q][p] = 1;
       }
 
       // Declaring variable A to store the output
       int A;
 
       for(i = 1; i <= n; i++)
       {
           A = 0;
           for(j = n; j > 0; j--)
           {
               k = C[j].index;
               if(arr[k][i] == 0)
               {
                   A = k;
                   break;
               }
           }
           printf("%d ", A);
       }
 
       printf("\n");
    }
 
    return 0;
}