golf-results-2020-summer

Task

Rules

• The program performs a simulation of an epidemic simulation and prints ASCII's map of people (see examples).
• The output must be printed to STDOUT.
• The output must have a newline char (\n) at the end.
• Program gets 2 arguments (argv)
• Arguments are always valid.
• First argument K is an integer defining the number of iterations.
• Second argument is a string representing the population separated with commas (see description of the XYSQ code below).
• Each line must have newline char (\n) at the end.
• The last line must not have any characters after newline char (\n).

Description

Inspiration for this golf is another simulation created by Washington Post (https://www.washingtonpost.com/graphics/2020/world/corona-simulator/).

The goal of this golf is to create a simulation of a virus spreading across the population.

$ ./task 10 22H0,33S0
........
........
........
.S......
....S...
........
........
........

The area is always 8x8 size.

Each person is described with the XYSQ code, where:

• X - position in X axis, from 0 to 7;
• Y - position in Y axis, from 0 to 7;
• S - State of the person, we have 3 states:
  • H - Healthy person, can be infected;
  • S - Sick person, can infect healthy person and after 14 iterations changes to R state;
  • R - Recovered person, cannot be infected;
• Q - Quarantine state, 0 or 1, if Q is 1< then the person can't move;
• Additionaly, the person has a hidden N value - it's a grain for random moving (please see step flow). Initial value is n = (x << 2)^7 * (y << 3)^5 where:
  • << is a bit shift
  • ^ is a XOR operation

Step flow

function next_iteration(P) {
    for (person in P) { // iterate in a sequence
        person.s = cure(person.s)
        person.n = gen_n(person.n)
        [new_x, new_y] = gen_new_cords(person)
        if (point {new_x, new_y} is free and person.q == 0) { 
            person.x = new_x
            person.y = new_y
        }
        if (person.s == H and in the neightbourhood (use Moore) is a sick individual) {
            // https://en.wikipedia.org/wiki/Moore_neighborhood
            person.s = S
        }
    }
}

function cure(state) {
    if (state == S and 14 iterations has passed since the individual got sick) {
        return R
    } else {
        return state
    }
}

function gen_n(n) {
    n ^= n << 13
    n ^= n >> 17
    n ^= n << 5
    return n % (1 << 30)
}

function gen_new_cords(person) {
    x = person.x
    y = person.y
    switch(person.n modulo 4) {
        case 0: x += 1
        case 1: x -= 1
        case 2: y += 1
        case 3: y -= 1
    }
    // wrap points, like in pacman game
    if (x >= WIDTH)  x -= WIDTH  else if (x < 0) x += WIDTH
    if (y >= HEIGHT) y -= HEIGHT else if (y < 0) y += HEIGHT
    return [x, y]
}

Examples

$ ./task 1 25H0,32S0,46R1,63H1,76S1
........
........
........
...S..H.
........
...H....
....R..S
........

$ ./task 2 25H0,32S0,46R1,63H1,76S1
........
........
........
....S.H.
...S....
........
....R..S
........

$ ./task 14 25H0,32S0,46R1,63H1,76S1
.R......
........
........
......S.
.......S
........
....R..R
........

$ ./task 20 25H0,32S0,46R1,63H1,76S1
.R......
........
........
......RR
........
........
....R..R
........