题解 | 小红的整数配对

n, k = map(int,input().split())
arr = list(map(int,input().split()))
sort_arr = sorted(arr,reverse=True)
i = 0
j = 1
visited = set()
score = 0
while i < n - 1:
    if sort_arr[i] - sort_arr[j] <= k:
        if i not in visited and j not in visited:
            score += sort_arr[i] * sort_arr[j]
            visited.add(i)
            visited.add(j)
            i = j+1
            j = i+1
            if j >= n:
                break
    else:
        i = i + 1
        j = j + 1
print(score)