64. 求幸存数之和

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

rl.on('line', function(line) {
    if (!this.nums) {
        this.nums = line.split(',').map(Number);
    } else if (!this.jump) {
        this.jump = Number(line);
    } else if (!this.left) {
        this.left  = Number(line);
        console.log(sumOfLeft(this.nums, this.jump, this.left));
    }
});
function sumOfLeft(nums, jump, left) {
    if (left >= nums.length) {
        return nums.reduce((acc, val) => acc + val, 0);
    }

    let list = nums.slice();
    let index = 0;
    while(list.length > left) {
        index = (index + jump + 1) % list.length;
        list.splice(index, 1);
        // 删除元素后，列表会变短，下一个起跳点应该向前移动一位
        index = index - 1;
    }
    return list.reduce((acc, val) => acc + val, 0);
}