fix a small bug in DummyHistoryHandler.java(proj2a)

[ceyewan]

I am a student from China. While working on proj2a, I found that the provided skeleton code did not produce the parabola and sinusoid as demonstrated in the documentation. Therefore, I modified this bug to achieve the correct demonstration.

The original code is as follows:

TimeSeries parabola = new TimeSeries();
for (int i = 1400; i < 1500; i += 1) {
    parabola.put(i, (i - 50.0) * (i - 50.0) + 3);
}
TimeSeries sinWave = new TimeSeries();
for (int i = 1400; i < 1500; i += 1) {
    sinWave.put(i, 1000 + 500 * Math.sin(i/100.0*2*Math.PI));
}

The image is as follows:

After modifying the code, it is as follows:

TimeSeries parabola = new TimeSeries();
for (int i = 0; i < 100; i += 1) {
    parabola.put(i, (i - 50.0) * (i - 50.0) + 3);
}
TimeSeries sinWave = new TimeSeries();
for (int i = 0; i < 100; i += 1) {
    sinWave.put(i, 1000 + 500 * Math.sin(i/100.0*2*Math.PI));
}

The image is as follows:

I would like to thank Berkeley, the professors, and the TAs for providing such great learning materials in CS61B.