[18주차] 풀이 추가

README.md

@@ -136,35 +136,7 @@
 | 23 | [땅따먹기](https://school.programmers.co.kr//learn/courses/30/lessons/12913) | [땅따먹기.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/땅따먹기.js) |
 | 24 | [멀쩡한 사각형](https://school.programmers.co.kr//learn/courses/30/lessons/62048) | [멀쩡한-사각형.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/멀쩡한-사각형.js) |
 | 25 | [메뉴 리뉴얼](https://school.programmers.co.kr//learn/courses/30/lessons/72411) | [메뉴-리뉴얼.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/메뉴-리뉴얼.js) |
-| 26 | [모음 사전](https://school.programmers.co.kr/undefined) | [모음-사전.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/모음-사전.js) |
-| 27 | [문자열 압축](https://school.programmers.co.kr//learn/courses/30/lessons/60057) | [문자열-압축.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/문자열-압축.js) |
-| 28 | [빛의 경로 사이클](https://school.programmers.co.kr//learn/courses/30/lessons/86052) | [빛의-경로-사이클.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/빛의-경로-사이클.js) |
-| 29 | [삼각 달팽이](https://school.programmers.co.kr//learn/courses/30/lessons/68645) | [삼각-달팽이.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/삼각-달팽이.js) |
-| 30 | [소수 찾기](https://school.programmers.co.kr//learn/courses/30/lessons/42839) | [소수-찾기.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/소수-찾기.js) |
-| 31 | [수식 최대화](https://school.programmers.co.kr//learn/courses/30/lessons/67257) | [수식-최대화.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/수식-최대화.js) |
-| 32 | [숫자의 표현](https://school.programmers.co.kr//learn/courses/30/lessons/12924) | [숫자의-표현.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/숫자의-표현.js) |
-| 33 | [스킬트리](https://school.programmers.co.kr//learn/courses/30/lessons/49993) | [스킬트리.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/스킬트리.js) |
-| 34 | [영어 끝말잇기](https://school.programmers.co.kr//learn/courses/30/lessons/12981) | [영어-끝말잇기.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/영어-끝말잇기.js) |
-| 35 | [예상 대진표](https://school.programmers.co.kr//learn/courses/30/lessons/12985) | [예상-대진표.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/예상-대진표.js) |
-| 36 | [오픈채팅방 ](https://school.programmers.co.kr//learn/courses/30/lessons/42888) | [오픈채팅방.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/오픈채팅방.js) |
-| 37 | [올바른 괄호](https://school.programmers.co.kr//learn/courses/30/lessons/12909) | [올바른-괄호.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/올바른-괄호.js) |
-| 38 | [위장](https://school.programmers.co.kr//learn/courses/30/lessons/42578) | [위장.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/위장.js) |
-| 39 | [점프와 순간 이동](https://school.programmers.co.kr//learn/courses/30/lessons/12980) | [점프와-순간-이동.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/점프와-순간-이동.js) |
-| 40 | [조이스틱](https://school.programmers.co.kr//learn/courses/30/lessons/42860) | [조이스틱.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/조이스틱.js) |
-| 41 | [주차 요금 계산](https://school.programmers.co.kr//learn/courses/30/lessons/92341) | [주차-요금-계산.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/주차-요금-계산.js) |
-| 42 | [짝지어 제거하기](https://school.programmers.co.kr//learn/courses/30/lessons/12973) | [짝지어-제거하기.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/짝지어-제거하기.js) |
-| 43 | [최댓값과 최솟값](https://school.programmers.co.kr//learn/courses/30/lessons/12939) | [최댓값과-최솟값.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/최댓값과-최솟값.js) |
-| 44 | [최솟값 만들기](https://school.programmers.co.kr//learn/courses/30/lessons/12941) | [최솟값-만들기.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/최솟값-만들기.js) |
-| 45 | [카펫](https://school.programmers.co.kr//learn/courses/30/lessons/42842) | [카펫.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/카펫.js) |
-| 46 | [큰 수 만들기](https://school.programmers.co.kr//learn/courses/30/lessons/42883) | [큰-수-만들기.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/큰-수-만들기.js) |
-| 47 | [타겟 넘버](https://school.programmers.co.kr//learn/courses/30/lessons/43165) | [타겟-넘버.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/타겟-넘버.js) |
-| 48 | [튜플](https://school.programmers.co.kr//learn/courses/30/lessons/64065) | [튜플.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/튜플.js) |
-| 49 | [프린터](https://school.programmers.co.kr//learn/courses/30/lessons/42587) | [프린터.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/프린터.js) |
-| 50 | [피보나치 수](https://school.programmers.co.kr//learn/courses/30/lessons/12945) | [피보나치-수.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/피보나치-수.js) |
-| 51 | [하노이의 탑](https://school.programmers.co.kr//learn/courses/30/lessons/12946) | [하노이의-탑.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/하노이의-탑.js) |
-| 52 | [행렬 테두리 회전하기](https://school.programmers.co.kr//learn/courses/30/lessons/77485) | [행렬-테두리-회전하기.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/행렬-테두리-회전하기.js) |
-| 53 | [행렬의 곱셈](https://school.programmers.co.kr//learn/courses/30/lessons/12949) | [행렬의-곱셈.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/행렬의-곱셈.js) |
-| 54 | [후보키](https://school.programmers.co.kr//learn/courses/30/lessons/42890) | [후보키.js](https://github.com/codeisneverodd/programmers-coding-test/blob/main/level-2/후보키.js) |
+
 
 ### Level 3 👨🏻‍💻(풀이 중..)
 

level-2/구명보트.js

@@ -40,4 +40,27 @@ function solution(people, limit) {
   }
 
   return count;
+}
+
+// 정답 3 - iHoHyeon
+function solution(people, limit) {
+  people.sort((a, b) => a - b); // 오름차순 정렬
+
+  let cnt = 0; // 구명보트 개수
+
+  let front = 0; // 가장 몸무게가 작은 사람의 index
+  let last = people.length; // 가장 몸무게가 큰 사람의 index
+
+  while (last > front) {
+    cnt++;
+
+    const now = people.pop();
+    last--;
+
+    if (now + people[front] <= limit) {
+      front++; // shift() 연산의 비효율로 인해 front 사용
+    }
+  }
+
+  return cnt;
 }

level-2/배달.js

@@ -0,0 +1,190 @@
+//https://github.com/codeisneverodd/programmers-coding-test
+//완벽한 정답이 아닙니다.
+
+//정답 1 - pereng11
+// 다익스트라 + 최소힙 O( N * logN ) 
+    // [목적지, 거리] 노드를 값으로 가지는, 거리에 대한 최소힙 
+class MinHeap{
+    constructor ()
+    {
+      this.heap = [ null ];
+    }
+    // 맨 끝에 노드를 삽입 후 위로 올라가면서 정렬
+    push ( val )
+    {
+          this.heap.push(val);
+          let childIdx = this.heap.length-1;
+          let parentIdx = Math.floor(childIdx / 2);
+          while(parentIdx > 0 && this.heap[parentIdx][1] > this.heap[childIdx][1]){
+            this.swap( childIdx, parentIdx );
+            childIdx = parentIdx;
+            parentIdx = Math.floor(childIdx / 2);
+          }
+    }
+    pop ()
+    {
+      if ( this.heap.length === 1 )
+      {
+        return undefined;
+      }
+      // 최소값은 빼두었다가 리턴하고, 가장 끝 값을 맨 위로 가져와 아래로 내려가면서 정렬
+      const minNode = this.heap[ 1 ];
+      this.heap[ 1 ] = this.heap[ this.heap.length - 1 ];
+      this.heap.pop();
+      let parentIdx = 1;
+      let leftChildIdx = 2;
+      let rightChildIdx = 3;
+      while ( parentIdx < this.heap.length )
+      {
+        // 자식이 없는 경우 
+        if ( !this.heap[ leftChildIdx ] )
+        {
+          break;
+        } // 왼쪽 자식만 있는 경우
+        else if ( !this.heap[ rightChildIdx ] )
+        {
+          if ( this.heap[ parentIdx ][ 1 ] > this.heap[ leftChildIdx ][ 1 ] )
+          {
+            this.swap( parentIdx, leftChildIdx );
+          }
+          break;
+          // 둘 중 하나가 부모보다 작을 때, 더 작은 쪽으로 정렬
+        } else if ( this.heap[ parentIdx ][ 1 ] > this.heap[ leftChildIdx ][ 1 ] || this.heap[ parentIdx ][ 1 ] > this.heap[ rightChildIdx ][ 1 ] )
+        {
+          const minChildIdx = this.heap[ leftChildIdx ][ 1 ] < this.heap[ rightChildIdx ][ 1 ] ? leftChildIdx : rightChildIdx;
+          this.swap( parentIdx, minChildIdx );
+          parentIdx = minChildIdx;
+          leftChildIdx = parentIdx * 2
+          rightChildIdx = parentIdx * 2 + 1;
+        } else
+        {
+          // 끝까지 내려가지 않았더라도 부모가 가장 작으면 정렬 중지
+          break;
+        }
+      }
+      return minNode;
+    }
+    swap ( idx1, idx2 )
+    {
+        [ this.heap[ idx1 ], this.heap[ idx2 ] ] = [ this.heap[ idx2 ], this.heap[ idx1 ] ];
+    }
+    length ()
+    {
+      return this.heap.length;
+    }
+}
+
+function solution ( N, road, K )
+{
+  const roadsTable = {}; //전체 도로 정보
+
+  // 도로 정보 초기화 roadTable[시작점] = [목적지, 거리] 배열
+  for ( let i = 1; i <= N; i++ )
+  {
+    roadsTable[ i ] = [];
+  }
+  road.forEach( road =>
+  {
+    let [ sp, ep, dist ] = road;
+    roadsTable[ sp ].push( [ ep, dist ] );
+    roadsTable[ ep ].push( [ sp, dist ] );
+  } );
+
+  function djikstra ( sp )
+  {
+    const visited = new Array( N + 1 ).fill( false ); //방문 확인 배열
+    const dist = new Array( N + 1 ).fill( Infinity ); //목표지점까지 거리
+    const heap = new MinHeap();
+
+    //시작점 삽입
+    heap.push( [sp, 0] );
+
+    // 가장 가까운 목적지부터 순서대로 방문
+    while ( heap.length() > 1 )
+    {
+      //힙에 저장된 목적지 중 가장 가까운 거리의 목적지를 꺼냄 [목적지, 거리]
+      const [ ep, val ] = heap.pop();
+      //아직 방문하지 않은 곳만 처리
+      if ( !visited[ ep ] )
+      {
+        //방문처리, 거리 저장
+        visited[ ep ] = true;
+        dist[ ep ] = val;
+        //방문 지점을 거쳐서 가는 다른 목적지 구하기
+        const nexts = roadsTable[ ep ];
+        if ( nexts )
+        {
+          nexts.forEach( n =>
+          {
+            let [ nextEp, nextVal ] = n;
+            if ( !visited[ nextEp ] ) //아직 방문하지 않은 곳일 경우, '지금까지의 거리 + 현재 위치에서의 거리'로 힙에 삽입
+            {
+              heap.push( [ nextEp, val + nextVal ] );
+            }
+          })
+        }
+      }
+    }
+    // 거리가 K이하인 지점의 개수 반환
+    const result = dist.filter( d => d <= K ).length;
+    return result;
+  }
+
+  const answer = djikstra( 1 );
+  return answer;
+}
+
+//정답 2 - pereng11 O(N * N);
+//다익스트라 + 선형탐색
+function solution ( N, road, K )
+{  
+  const roadsTable = {}; //전체 도로 정보
+
+  // 도로 정보 초기화 roadTable[시작점] = [목적지, 거리] 배열
+  for ( let i = 1; i <= N; i++ )
+  {
+    roadsTable[ i ] = [];
+  }
+  road.forEach( road =>
+  {
+    let [ sp, ep, dist ] = road;
+    roadsTable[ sp ].push( [ ep, dist ] );
+    roadsTable[ ep ].push( [ sp, dist ] );
+  } );
+
+  function djikstra ( sp )
+  {
+    const dist = new Array( N + 1 ).fill( Infinity ); //목표지점까지 거리
+    const queue = [];
+
+    queue.push( [sp, 0] );
+
+    while ( queue.length > 0 )
+    {
+      const [ ep, val ] = queue.shift();
+      if ( dist[ ep ] > val )
+      {
+        dist[ ep ] = val;
+        const nexts = roadsTable[ ep ];
+        if ( nexts )
+        {
+          nexts.forEach( n =>
+            {
+              let [ nextEp, nextVal ] = n;
+              //거리가 더 줄어드는 경우, '지금까지의 거리 + 현재 위치에서의 거리'로 힙에 삽입
+              if ( dist[ nextEp ] > val + nextVal )
+              {
+                queue.push( [ nextEp, val + nextVal ] );
+              }
+            } );
+          }
+      }
+    }
+      // 거리가 K이하인 지점의 개수 반환
+    const result = dist.filter( d => d <= K ).length;
+    return result;
+  }
+
+  const answer = djikstra( 1 );
+  return answer;
+}