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)
MATCHES Playing with Matches | HRDSEQ Hard Sequence |
DRCHEF Doctor Chef | 559. Maximum Depth of N-ary Tree |
821. Shortest Distance to a Character | 1441. Build an Array With Stack Operations |
1356. Sort Integers by The Number of 1 Bits | 922. Sort Array By Parity II |
344. Reverse String | 1047. Remove All Adjacent Duplicates In String |
977. Squares of a Sorted Array | 852. Peak Index in a Mountain Array |
461. Hamming Distance | 1748. Sum of Unique Elements |
897. Increasing Order Search Tree | 905. Sort Array By Parity |
1351. Count Negative Numbers in a Sorted Matrix | 617. Merge Two Binary Trees |
1450. Number of Students Doing Homework at a Given Time | 700. Search in a Binary Search Tree |
590. N-ary Tree Postorder Traversal | 589. N-ary Tree Preorder Traversal |
1299. Replace Elements with Greatest Element on Right Side | 1768. Merge Strings Alternately |
561. Array Partition I | 1374. Generate a String With Characters That Have Odd Counts |
1822. Sign of the Product of an Array | 1464. Maximum Product of Two Elements in an Array |
1323. Maximum 69 Number | 832. Flipping an Image |