难度: 简单
/**
* @param {string} s
* @return {string}
*/
var removeDuplicates = function (s) {
const stack = []
for (const i of s) {
if (stack.length && stack[stack.length - 1] === i) {
stack.pop();
} else {
stack.push(i);
}
}
return stack.join('')
};