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1.5. Counting nucleotides
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In this session, don't panic. We will design our first algorithm. This algorithm is forcounting nucleotides. The idea here is that as an input,you have a sequence of nucleotides, of bases, of letters, of characters which ends with a star symbol, here. And, you want to count the number of A,C, G and T, and then the frequencies. To write an algorithm in thispseudo code language, you need first to declare on which objector variables you will work. Here, we declare severalinteger variables. What does it mean integer variables? That is a variable, the value of which can be an integer: 1, 2, 3, minus 9 and so on. So, integer is what we call "akeyword" which belongs to the pseudo code language. We also need to declare a sequence as a sequence of characters, a character string. The length of which is not specified. It starts in one andit ends somewhere. Sequence of one is the first character of the sequence. Then, you have to initialize your variable. That is to give the first value.
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