1255B - Fridge Lockers - CodeForces Solution

for _ in range(int(input())):
    n,m=map(int,input().split())
    l=list(map(int,input().split()))

    if n<3 or m<n:
        print(-1)
    else:
        i,i1=-1,float('inf')
        s=0

        for x in range(n):
            if l[x]<i1:
                i1=l[x]
                i=x
            s+=l[x]
            

        j,j1=-1,float('inf')
        for x in range(n):
            if x!=i and l[x]<j1:
                j1=l[x]
                j=x
                
        print((2*s)+((m-n)*(i1+j1)))
        
        for x in range(n-1):
            print(x+1,x+2)
        print(n,1)

        for x in range(m-n):
            print(i+1,j+1)