권지호

jiho/0001-two-sum/0001-two-sum.ts

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+function twoSum(nums: number[], target: number): number[] {
+    const map = new Map ()
+
+    for(const [i, num] of nums.entries()) {
+        const rest = target - num
+
+        if(map.has(rest)) {
+            return [i, map.get(rest)]
+        }
+
+        map.set(num, i)
+    }
+
+    return []
+};

jiho/0009-palindrome-number/0009-palindrome-number.ts

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+function get(x:number) {
+    let count = 1
+    while(Math.floor(x / count) >= 10) {
+        count *=10
+    }
+
+    return count
+}
+
+function isPalindrome(x: number): boolean {
+    if(x < 0) return false
+
+    let div= get(x)
+
+    while(x > 0) {
+        let left = Math.floor(x/div)
+        let right = x % 10
+
+        if(left !== right) return false
+
+        x = Math.floor((x % div) / 10)
+        div /= 100
+    }
+
+    return true
+};

jiho/0020-valid-parentheses/0020-valid-parentheses.ts

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+function isValid(s: string): boolean {
+    if(s.length % 2 === 1) return false 
+
+    const stock = []
+
+    for(const char of s) {
+
+        if(stock.at(-1) === '(' && char === ')') {
+            stock.pop()
+            continue
+        }
+        if(stock.at(-1) === '{' && char === '}') {
+            stock.pop()
+            continue
+        }
+        if(stock.at(-1) === '[' && char === ']') {
+            stock.pop()
+            continue
+        }
+
+        stock.push(char)
+    }
+
+    return stock.length === 0 
+};

jiho/0020-valid-parentheses/README.md

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+<h2><a href="https://leetcode.com/problems/valid-parentheses">20. Valid Parentheses</a></h2><h3>Easy</h3><hr><p>Given a string <code>s</code> containing just the characters <code>&#39;(&#39;</code>, <code>&#39;)&#39;</code>, <code>&#39;{&#39;</code>, <code>&#39;}&#39;</code>, <code>&#39;[&#39;</code> and <code>&#39;]&#39;</code>, determine if the input string is valid.</p>
+
+<p>An input string is valid if:</p>
+
+<ol>
+	<li>Open brackets must be closed by the same type of brackets.</li>
+	<li>Open brackets must be closed in the correct order.</li>
+	<li>Every close bracket has a corresponding open bracket of the same type.</li>
+</ol>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">s = &quot;()&quot;</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">true</span></p>
+</div>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">s = &quot;()[]{}&quot;</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">true</span></p>
+</div>
+
+<p><strong class="example">Example 3:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">s = &quot;(]&quot;</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">false</span></p>
+</div>
+
+<p><strong class="example">Example 4:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">s = &quot;([])&quot;</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">true</span></p>
+</div>
+
+<p><strong class="example">Example 5:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">s = &quot;([)]&quot;</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">false</span></p>
+</div>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
+	<li><code>s</code> consists of parentheses only <code>&#39;()[]{}&#39;</code>.</li>
+</ul>

jiho/0049-group-anagrams/0049-group-anagrams.ts

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+function groupAnagrams(strs: string[]): string[][] {
+    // 목표: 애나그램끼리 그룹핑
+    // 완전탐색 필요. 현재의 요소와 모든 요소를 비교해봐야 한다. 
+
+    const result = new Map()
+
+    for(const str of strs) {
+        const key = str.split('').sort().join('')
+
+        if(!result.has(key)) {
+            result.set(key, [])
+        }
+
+        result.get(key).push(str)
+    }
+
+    return Array.from(result.values())
+};

jiho/0049-group-anagrams/README.md

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+<h2><a href="https://leetcode.com/problems/group-anagrams">49. Group Anagrams</a></h2><h3>Medium</h3><hr><p>Given an array of strings <code>strs</code>, group the <span data-keyword="anagram">anagrams</span> together. You can return the answer in <strong>any order</strong>.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">strs = [&quot;eat&quot;,&quot;tea&quot;,&quot;tan&quot;,&quot;ate&quot;,&quot;nat&quot;,&quot;bat&quot;]</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">[[&quot;bat&quot;],[&quot;nat&quot;,&quot;tan&quot;],[&quot;ate&quot;,&quot;eat&quot;,&quot;tea&quot;]]</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<ul>
+	<li>There is no string in strs that can be rearranged to form <code>&quot;bat&quot;</code>.</li>
+	<li>The strings <code>&quot;nat&quot;</code> and <code>&quot;tan&quot;</code> are anagrams as they can be rearranged to form each other.</li>
+	<li>The strings <code>&quot;ate&quot;</code>, <code>&quot;eat&quot;</code>, and <code>&quot;tea&quot;</code> are anagrams as they can be rearranged to form each other.</li>
+</ul>
+</div>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">strs = [&quot;&quot;]</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">[[&quot;&quot;]]</span></p>
+</div>
+
+<p><strong class="example">Example 3:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">strs = [&quot;a&quot;]</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">[[&quot;a&quot;]]</span></p>
+</div>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= strs.length &lt;= 10<sup>4</sup></code></li>
+	<li><code>0 &lt;= strs[i].length &lt;= 100</code></li>
+	<li><code>strs[i]</code> consists of lowercase English letters.</li>
+</ul>

jiho/0054-spiral-matrix/0054-spiral-matrix.ts

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+function spiralOrder(matrix: number[][]): number[] {
+    // 무엇을 기억해? 숫자 (x) -> 좌표!
+    // 한번 움직일 때 바뀌는 것 위치
+    // 언제 종료? 다 돌았을 때
+    // 예외는? -> 그리드 모서리? 각 경계
+    const result = []
+    let top = 0
+    let right = matrix[0].length -1
+    let left = 0
+    let bottom = matrix.length -1
+
+    while(top <= bottom && left <= right){
+        for(let col = left; col <=right; col++ ) {
+            result.push(matrix[top][col])
+        }
+        top+=1
+
+        for(let row = top; row <= bottom; row++) {
+            result.push(matrix[row][right])
+        }
+        right--
+
+        if(top <= bottom) {
+            for(let col = right; col >= left; col--) {
+                result.push(matrix[bottom][col])
+            }
+            bottom--
+        }
+
+        if(left <= right) {
+            for(let row = bottom; row >= top; row--){
+                result.push(matrix[row][left])
+            }
+            left++
+        }
+    }
+
+    return result
+};

jiho/0054-spiral-matrix/README.md

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+<h2><a href="https://leetcode.com/problems/spiral-matrix">54. Spiral Matrix</a></h2><h3>Medium</h3><hr><p>Given an <code>m x n</code> <code>matrix</code>, return <em>all elements of the</em> <code>matrix</code> <em>in spiral order</em>.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+<img alt="" src="https://assets.leetcode.com/uploads/2020/11/13/spiral1.jpg" style="width: 242px; height: 242px;" />
+<pre>
+<strong>Input:</strong> matrix = [[1,2,3],[4,5,6],[7,8,9]]
+<strong>Output:</strong> [1,2,3,6,9,8,7,4,5]
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+<img alt="" src="https://assets.leetcode.com/uploads/2020/11/13/spiral.jpg" style="width: 322px; height: 242px;" />
+<pre>
+<strong>Input:</strong> matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
+<strong>Output:</strong> [1,2,3,4,8,12,11,10,9,5,6,7]
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>m == matrix.length</code></li>
+	<li><code>n == matrix[i].length</code></li>
+	<li><code>1 &lt;= m, n &lt;= 10</code></li>
+	<li><code>-100 &lt;= matrix[i][j] &lt;= 100</code></li>
+</ul>

jiho/0059-spiral-matrix-ii/0059-spiral-matrix-ii.ts

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+function generateMatrix(n: number): number[][] {
+    const matrix = Array.from({ length: n }, (_, i) => Array(n).fill(0));
+    let num = 0
+    let top =0
+    let left = 0
+    let right = n-1
+    let bottom = n-1
+
+
+    while(top <= bottom && left <= right) {
+        //왼 -> 오
+        for(let col = left; col <= right; col++){
+            matrix[top][col] = num+=1
+        }
+        top++
+
+        //위 -> 아래 
+        for(let row = top; row <= bottom; row++) {
+            matrix[row][right] = num+=1
+        }
+        right--
+
+        //오 -> 왼
+        if(left <= right) {
+            for(let col = right; col >= left; col--) {
+                matrix[bottom][col] = num+=1
+            }
+        }
+        bottom--
+
+        // 아래 -> 위
+        if(top <= bottom) {
+            for(let row = bottom; row >= top; row--) {
+                matrix[row][left] = num+=1
+            }
+        }
+        left++
+    }
+
+    return matrix
+};

jiho/0059-spiral-matrix-ii/README.md

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+<h2><a href="https://leetcode.com/problems/spiral-matrix-ii">59. Spiral Matrix II</a></h2><h3>Medium</h3><hr><p>Given a positive integer <code>n</code>, generate an <code>n x n</code> <code>matrix</code> filled with elements from <code>1</code> to <code>n<sup>2</sup></code> in spiral order.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+<img alt="" src="https://assets.leetcode.com/uploads/2020/11/13/spiraln.jpg" style="width: 242px; height: 242px;" />
+<pre>
+<strong>Input:</strong> n = 3
+<strong>Output:</strong> [[1,2,3],[8,9,4],[7,6,5]]
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> n = 1
+<strong>Output:</strong> [[1]]
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= n &lt;= 20</code></li>
+</ul>

jiho/0062-unique-paths/0062-unique-paths.ts

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+function uniquePaths(m: number, n: number): number {
+    const dp = Array.from({length: m}, () => Array(n).fill(0))
+
+    dp[0][0] = 1
+    for(let i = 1; i < m; i++){
+        dp[i][0] = 1
+    }
+
+    for(let j =1; j<n; j ++) {
+        dp[0][j] = 1
+    }
+
+    for(let i = 1; i < m ; i++) {
+        for(let j = 1; j <n ; j++) {
+            dp[i][j] = dp[i-1][j] + dp[i][j-1]
+        }
+    }
+
+    return dp[m-1][n-1]
+};

jiho/0062-unique-paths/README.md

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+<h2><a href="https://leetcode.com/problems/unique-paths">62. Unique Paths</a></h2><h3>Medium</h3><hr><p>There is a robot on an <code>m x n</code> grid. The robot is initially located at the <strong>top-left corner</strong> (i.e., <code>grid[0][0]</code>). The robot tries to move to the <strong>bottom-right corner</strong> (i.e., <code>grid[m - 1][n - 1]</code>). The robot can only move either down or right at any point in time.</p>
+
+<p>Given the two integers <code>m</code> and <code>n</code>, return <em>the number of possible unique paths that the robot can take to reach the bottom-right corner</em>.</p>
+
+<p>The test cases are generated so that the answer will be less than or equal to <code>2 * 10<sup>9</sup></code>.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+<img src="https://assets.leetcode.com/uploads/2018/10/22/robot_maze.png" style="width: 400px; height: 183px;" />
+<pre>
+<strong>Input:</strong> m = 3, n = 7
+<strong>Output:</strong> 28
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> m = 3, n = 2
+<strong>Output:</strong> 3
+<strong>Explanation:</strong> From the top-left corner, there are a total of 3 ways to reach the bottom-right corner:
+1. Right -&gt; Down -&gt; Down
+2. Down -&gt; Down -&gt; Right
+3. Down -&gt; Right -&gt; Down
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= m, n &lt;= 100</code></li>
+</ul>