25. 最优结果的a数组数量

const readline = require('readline');
const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
});

let a;
let b;
let maxMatch = 0;
let op = 0;
function swap(array, i,j) {
    [arr[i], arr[j]] = [arr[j], arr[i]];
}
function findMaxMatch(a, b, index) {
    if (index === a.length) {
        let match = 0;
        for(let i=0; i<a.length; i++) {
            if (a[i] > b[i]) {
                match++;
            }
        }
        maxMatch = Math.max(maxMatch, match);
        return;
    }
    for(let i=index; i<a.length; i++) {
        swap(a, index, i);
        findMaxMatch(a, b, index+1);
        swap(a, index, i);//回溯
    }
}
function permute(a, index, b) {
    if (index === a.length) {
        let match = 0;
        for(let i=0;i<a.length; i++) {
            if (a[i] > b[i]) {
                match++;
            }
        }
        if (match === maxMatch) {
            op++;
        }
        return;
    }
    for(let i=index; i<a.length; i++) {
        swap(a, index, i);
        permute(a, index+1, b);
        swap(a, index, i);
    }
}
rl.on('line', (line) => {
    const inputs = line.split(' ').map(Number);
    if (!a) {
        a = inputs;
    } else {
        b = inputs;
    }
});
rl.on('close', () => {
    b.sort((x,y)=>x-y);
    findMaxMatch(a, b, 0);
    permute(a, 0, b);
    console.log(op);
})