substitute.js

function substitute(input) {
    let index = 0;
    let num1IntBegin = Number(input[index]);
    index++;
    let num2IntBegin = Number(input[index]);
    index++;
    let num1Int2Begin = Number(input[index]);
    index++;
    let num2Int2Begin = Number(input[index]);
    index++;
    let swapsCounter = 0;
    let swapsLimit = false;

    for (let i = num1IntBegin; i <= 8; i++) {
        for (let i2 = 9; i2 >= num2IntBegin; i2--) {
            for (let i3 = num1Int2Begin; i3 <= 8; i3++) {
                for (let i4 = 9; i4 >= num2Int2Begin; i4--) {
                    let result = "";
                    let result2 = "";
                    if (i % 2 === 0 && i2 % 2 !== 0 && i3 % 2 === 0 && i4 % 2 !== 0) {
                        result += "" + i + i2;
                        result2 += "" + i3 + i4;
                        if (swapsCounter < 6) {
                            if (result !== result2) {
                                swapsCounter++;
                                console.log(`${result} - ${result2}`);
                            } else {
                                console.log("Cannot change the same player.");
                            }
                        } else {
                            break;
                        }
                    }
                }
            }
        }
    }
}

substitute(["6", "7", "5", "6"]);