136.只出现一次的数字

/*
 * @lc app=leetcode.cn id=136 lang=typescript
 *
 * [136] 只出现一次的数字
 */

// @lc code=start
function singleNumber(nums: number[]): number {
	if (nums.length === 0) return 0;
	let count: number = 0;
	nums.map((el) => {
		let curent = el;    
		let start = nums.indexOf(curent);
		let end = nums.lastIndexOf(curent);
		if (start === end) {
			count = el;
		}
	});
	return count;
}
// @lc code=end