august-week1-problem7.js

/**
 * @param {number[]} nums
 * @return {number[]}
 */
var findDuplicates = function(nums) {
    var result = [];
    for(var i = 0; i<nums.length; i++)
    {
        var index = Math.abs(nums[i])-1;
        if(nums[index] < 0) result.push(index+1);
        nums[index] = -nums[index];
    }
    return result;
};