HackerRank ‘Mars Exploration’ Solution

Short Problem Definition:

Sami’s spaceship crashed on Mars! She sends a series of SOS messages to Earth for help.


Mars Exploration


time complexity is O(N)

space complexity is O(1)


We know that the message is basically a lot of concatenated SOS strings. There is no magic to this one.

S = raw_input().strip()

errors = 0

for i in xrange(len(S)):
    if i % 3 == 0 and S[i] != 'S':
        errors += 1
    if i % 3 == 1 and S[i] != 'O':
        errors += 1
    if i % 3 == 2 and S[i] != 'S':
        errors += 1
print errors

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