Count students from each city

Now use CityTown as the key and a student count as the value. Each record increments exactly one city. This is the same create-or-increment pattern as word lengths; only the chosen key changes. You no longer need separate counters named ChennaiCount, MaduraiCount and so on.

cityCount = {}
foreach X in scores {
    city = X.CityTown
    if (not isKey(cityCount,city)) {
        cityCount[city] = 0
    }
    cityCount[city] = cityCount[city] + 1
}

Use consistent labels. “Bengaluru” is the dataset label; the spoken lecture sometimes says Bangalore. A deliberate alias map can combine known alternatives. Do not automatically merge unrelated places just because their names look similar.