217.存在重复元素

/**
 * @param {number[]} nums
 * @return {boolean}
 */
var containsDuplicate = function (nums) {
    for (var i = 0; i < nums.length; i++) {
        for (var j = i + 1; j < nums.length; j++) {
            if (nums[i] === nums[j]) {
                return true
            }
        }
    }
    return false
};

var containsDuplicate = function (nums) {
    var map = {}
    for (var i = 0; i < nums.length; i++) {
        map[nums[i]] = true
    }
    if(Object.keys(map).length !== nums.length) {
        return true
    } else {
        return false
    }
};

console.log(containsDuplicate([1,2,3,1]));
console.log(containsDuplicate([1,2,3,4]));
console.log(containsDuplicate([1,1,1,3,3,4,3,2,4,2]));