Freshman's Database

# We have managed to create a database with cycles

n = input()

# Array format - each entry in the array points to another entry in the array
array = [0] + [int(x) for x in input().split()]

visited = [-1] * (int(n) + 1)
cycles = 0

for i in range(1, len(array)):
    # Start from node i

    # Does node i have a parent?
    #if has_parent[i] == True:
    #    continue

    # Node does not have a parent, start DFS from this node
    #
    # Thankfully nobody can have more than one parent (only multiple children)
    latest = i
    
    while True:
        if visited[latest] == i:
            cycles += 1
            #print("cycle", i, latest)
            break
        
        # Already would have seen this cycle
        if visited[latest] > -1:
            #print("skip", i, latest, visited[latest])
            break
        
        visited[latest] = i
        latest = array[latest]

print(cycles)

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: TIME LIMIT EXCEEDED

Test 4

Verdict: TIME LIMIT EXCEEDED

Test 5

Verdict: TIME LIMIT EXCEEDED

Test 6

Verdict: TIME LIMIT EXCEEDED

Test 7

Verdict: TIME LIMIT EXCEEDED

Test 8

Verdict: TIME LIMIT EXCEEDED

Test 9

Verdict: TIME LIMIT EXCEEDED

Test 10

Verdict: TIME LIMIT EXCEEDED