const _permute = (string) => {
	let flag = new Array(string.length).fill(0);
	const len = string.length;
	let result = [];
	let res = "";
	function d() {
		if (res.length === len) {
			result.push(res);
			res = "";
			// res.slice(-1);
			// flag = new Array(string.length).fill(0);
			return;
		}
		for (let i = 0; i < len; ++i) {
			if (!flag[i]) {
				let temp = res;
				flag[i] = 1;
				res = res + string[i];
				d();
				flag[i] = 0;
				res = temp;
			}
		}
	}
	d();
	console.log(result);
	return result;
};