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[byol-han] WEEK 01 solutions #1138

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Apr 6, 2025
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9 changes: 9 additions & 0 deletions contains-duplicate/byol-han.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
// Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct.
/**
* @param {number[]} nums
* @return {boolean}
*/
var containsDuplicate = function (nums) {
const uniqueSet = new Set(nums);
return uniqueSet.size !== nums.length;
};
17 changes: 17 additions & 0 deletions house-robber/byol-han.js
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/**
* @param {number[]} nums
* @return {number}
*/
var rob = function (nums) {
if (nums.length === 0) return 0;
if (nums.length === 1) return nums[0];

let dp = [];
dp[0] = nums[0];
dp[1] = Math.max(nums[0], nums[1]);

for (let i = 2; i < nums.length; i++) {
dp[i] = Math.max(dp[i - 1], dp[i - 2] + nums[i]);
}
return dp[nums.length - 1];
};
23 changes: 23 additions & 0 deletions longest-consecutive-sequence/byol-han.js
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/**
* @param {number[]} nums
* @return {number}
*/
var longestConsecutive = function (nums) {
if (nums.length === 0) return nums.length;

const setNums = new Set(nums);
const sortNums = [...setNums].sort((a, b) => a - b);

let longest = 1;
let currentlength = 1;

for (let i = 0; i < sortNums.length; i++) {
if (sortNums[i] + 1 === sortNums[i + 1]) {
currentlength++;
longest = Math.max(longest, currentlength);
} else {
currentlength = 1;
}
}
return longest;
};
21 changes: 21 additions & 0 deletions top-k-frequent-elements/byol-han.js
Original file line number Diff line number Diff line change
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/**
* @param {number[]} nums
* @param {number} k
* @return {number[]}
*/
var topKFrequent = function (nums, k) {
const freqMap = new Map();

// 빈도수 계산
for (const num of nums) {
freqMap.set(num, (freqMap.get(num) || 0) + 1);
}

// Min Heap을 사용해서 상위 k개만 유지
return Array.from(freqMap.entries()) // [ [num, count], [num, count], ... ]
.sort((a, b) => b[1] - a[1]) // 빈도수를 기준으로 내림차순 정렬
.slice(0, k) // 상위 k개 선택
.map((entry) => entry[0]); // 숫자만 추출

return result;
};
22 changes: 22 additions & 0 deletions two-sum/byol-han.js
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// Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

// You may assume that each input would have exactly one solution, and you may not use the same element twice.

// You can return the answer in any order.

/**
* @param {number[]} nums
* @param {number} target
* @return {number[]}
*/
var twoSum = function (nums, target) {
let result = [];
for (let i = 0; i < nums.length; i++) {
for (let j = i + 1; j < nums.length; j++) {
if (nums[i] + nums[j] === target) {
return [i, j];
}
}
}
return result;
};