Pair sort

count = int(input())
nums = [int(aa)-1 for aa in input().strip().split(" ")]

# numsTmp = nums[:]
# print(nums)
# print(nums,end="\n\n")
numsPosDict = [[-1,-1] for _ in range(count)]
for ii in range(count*2):
    # print(nums[ii], ii)
    if numsPosDict[nums[ii]][0] == -1:
        numsPosDict[nums[ii]][0] = ii
    else:
        numsPosDict[nums[ii]][1] = ii
# print(numsPosDict)

swaps = [[-1,-1] for _ in range(count-1)]
for ii in range(count-1):
    # print(ii,numsPosDict[nums[ii*2]])
    swaps[ii][0] = ii*2+1
    # swaps[ii][1] = numsPosDict[nums[ii*2]][1]
    swaps[ii][1] = max(numsPosDict[nums[ii*2]])#[1]

    tmpToMove = nums[swaps[ii][0]]
    # tmpToMovePos = ii*2+1
    tmp = nums[swaps[ii][1]]
    # tmpPos = swaps[ii][1]
    nums[swaps[ii][1]] = tmpToMove
    nums[ii*2+1] = tmp

    if numsPosDict[tmpToMove][0] < numsPosDict[tmpToMove][1]:
        numsPosDict[tmpToMove][0] = swaps[ii][1]
    else:
        numsPosDict[tmpToMove][1] = swaps[ii][1]

    numsPosDict[tmp][1] = ii*2+1

    # print(swaps[ii])
    # print(nums)
    # print(numsPosDict)
    # print()
print(len(swaps))
for aa, bb in swaps:
    print(aa+1,bb+1)
# print(nums)
# for aa, bb in swaps:
#     numsTmp
# print(numsPosDict)

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED