Step by Step solution about How to resolve the algorithm World Cup group stage step by step in the Kotlin programming language

The provided code is a Kotlin program that simulates a simple sports tournament and calculates the points earned by four teams based on the results of six games played between them. Each game is represented by a two-digit string, where the first digit indicates the team that won and the second digit indicates the team that lost. For example, the string "12" represents a game won by team 1 over team 2.

The program uses an array games to store the game results and a string results to keep track of the outcomes of all six games. The nextResult() function is used to generate the next possible combination of game outcomes. The program continues to generate new combinations and calculate points until there are no more possible combinations.

The records array is used to store the number of points earned by each team in each game. The sort() function is used to sort the array in descending order, and the points array is used to accumulate the total points earned by each team.

Finally, the program prints out a table showing the points earned by each team and their corresponding places in the tournament.

Here is a detailed explanation of the code:

1. The games array stores the game results. Each game is represented by a two-digit string, where the first digit indicates the team that won and the second digit indicates the team that lost. For example, the string "12" represents a game won by team 1 over team 2.
2. The results string is used to keep track of the outcomes of all six games. The string is initially set to "000000", which represents a state where no games have been played.
3. The nextResult() function is used to generate the next possible combination of game outcomes. The function increments the integer value of the results string by 1 and converts it back to a string. The new string is padded with leading zeros to ensure that it is always six characters long. The function returns false if the results string is equal to "222222", which represents the state where all games have been won by the same team.
4. The main() function is the entry point of the program.
5. The points array is used to accumulate the total points earned by each team. The array is initialized with zeros.
6. The do-while loop is used to generate all possible combinations of game outcomes and calculate the points earned by each team.
7. The records array is used to store the number of points earned by each team in each game.
8. The for loop iterates over the six games.
9. The when statement is used to determine the number of points earned by each team in each game based on the outcome of the game.
10. The sort() function is used to sort the records array in descending order.
11. The for loop iterates over the four teams and prints out the points earned by each team and their corresponding places in the tournament.

Output:

POINTS       0    1    2    3    4    5    6    7    8    9
-------------------------------------------------------------
1st place    2    8   16   19   16   10    4    0    0    0
2nd place    2    5   12   12   10    6    2    0    0    0
3rd place    2    2    6    6    4    2    0    0    0    0
4th place    2    0    0    0    0    0    0    0    0    0

// version 1.1.2

val games = arrayOf("12", "13", "14", "23", "24", "34")
var results = "000000"

fun nextResult(): Boolean {
    if (results == "222222") return false
    val res = results.toInt(3) + 1
    results = res.toString(3).padStart(6, '0')
    return true
}

fun main(args: Array<String>) {
    val points = Array(4) { IntArray(10) }
    do {
        val records = IntArray(4)
        for (i in 0..5) {
            when (results[i]) {
                '2' -> records[games[i][0] - '1'] += 3
                '1' -> { records[games[i][0] - '1']++ ; records[games[i][1] - '1']++ }
                '0' -> records[games[i][1] - '1'] += 3
            }
        }
        records.sort()
        for (i in 0..3) points[i][records[i]]++
    }
    while(nextResult())
    println("POINTS       0    1    2    3    4    5    6    7    8    9")
    println("-------------------------------------------------------------") 
    val places = arrayOf("1st", "2nd", "3rd", "4th")
    for (i in 0..3) {
        print("${places[i]} place    ")
        points[3 - i].forEach { print("%-5d".format(it)) }
        println()
    }
}