11. 分月饼

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

rl.on('line', (line) => {
    let [m, n] = line.split(' ').map(Number);
    console.log(distribute(m, n, n, 0, new Array(m).fill(0)));
});

// 员工数量、剩余月饼数量、当前允许最大月饼数量、当前处理员工的索引、记录每个员工分配的月饼数
function distribute(m, remain, max, index, distribution) {
    if (index = m - 1) {
        if (remain <= max && (index === 0 || Math.abs(distribution[index - 1] - remain) <= 3)) {
            return 1;
        }
        return 0;
    }

    let ways = 0;
    let start = index === 0 ? 1 : distribution[index - 1] - 3;
    let end = Math.min(remain - (m - index - 1), max);
    for(let i=start; i<=end; i++) {
        distribution[i] = i;
        if(index === 0 || Math.abs(distribution[index - 1] - i) <=3) {
            ways += distribute(m, remain - i, i, index+1, distribution);
        }
    }
    return ways;
}