solve: 코딩테스트 문제 풀이 - 16일차

Author: OhChangEun

2025-08-28/오창은/[solved] 프로그래머스_가장 큰 정사각형 찾기.java

@@ -0,0 +1,25 @@
+class Solution
+{
+    public int solution(int [][]board)
+    {
+		int n = board.length;
+        int m = board[0].length;
+        
+        int[][] dp = new int[n][m];
+        int maxLen = 0;
+        for (int i=0; i<n; i++) {
+            for (int j=0; j<m; j++) {
+               	if (board[i][j] == 1) {
+                    if (i == 0 || j == 0) {
+                        dp[i][j] = board[i][j];
+                    } else {
+                        dp[i][j] = Math.min(Math.min(dp[i-1][j], dp[i][j-1]), dp[i-1][j-1]) + 1;
+                    }
+                }
+                maxLen = Math.max(maxLen, dp[i][j]);
+            }
+        }
+        
+        return maxLen * maxLen;
+    }
+}

2025-08-28/오창은/[solved] 프로그래머스_리코쳇 로봇.java

@@ -0,0 +1,83 @@
+import java.util.*;
+
+class Solution {
+    int[] dx = {0, 0, -1, 1};
+    int[] dy = {1, -1, 0, 0};
+    
+    int[] start;
+    int[] lever;
+    int[] end;
+    
+    int n,m;
+    char[][] map;
+   
+    public int solution(String[] maps) {
+        int answer = 0;
+       
+        n = maps.length;
+        m = maps[0].length();
+        map = new char[n][m];
+        for (int i=0; i<n; i++) {
+            char[] row = maps[i].toCharArray();
+            for (int j=0; j<m; j++) {
+            	map[i][j] = row[j];
+                
+                if (row[j] == 'S') {
+                    start = new int[] {i, j};
+                } else if (row[j] == 'L') {
+                    lever = new int[] {i, j};
+                } else if (row[j] == 'E') {
+                    end = new int[] {i, j};
+                }
+                
+            }
+        }
+       
+        int toLever = bfs(start, lever);
+        if (toLever == -1) return -1;
+        
+        int toEnd = bfs(lever, end);
+        if (toEnd == -1) return -1;
+        
+        // System.out.println(start[0] + " " + start[1]);
+        // System.out.println(lever[0] + " " + lever[1]);
+        
+        return toLever + toEnd;
+    }
+   
+    public int bfs(int[] start, int[] end) {
+    	int[][] distance = new int[n][m];
+      	for (int i=0; i<n; i++) {
+            Arrays.fill(distance[i], -1);
+        } 
+        
+        Queue<int[]> queue = new LinkedList<>();
+        int startY = start[0];
+        int startX = start[1];
+       	queue.offer(new int[] {startY, startX});
+      	distance[startY][startX] = 0;
+        
+        while (!queue.isEmpty()) {
+            int[] curr = queue.poll();
+         	int cx = curr[1];
+         	int cy = curr[0];
+           
+            if (cx == end[1] && cy == end[0]) {
+                return distance[cy][cx];
+            }
+            
+            for (int i=0; i<4; i++) {
+            	int ny = cy + dy[i];
+            	int nx = cx + dx[i];
+                
+                if (nx >= 0 && nx < m && ny >=0 && ny < n) {
+                    if (map[ny][nx] != 'X' && distance[ny][nx] == -1) {
+                       	distance[ny][nx] = distance[cy][cx] + 1;
+                        queue.offer(new int[]{ny, nx});
+                    }
+                }
+            }
+        }
+        return -1;
+    }
+}

2025-08-28/오창은/[solved] 프로그래머스_무인도 여행.java

@@ -0,0 +1,63 @@
+import java.util.*;
+
+class Solution {
+    int height, width;
+    int[] dx = { 0, 0, -1, 1 };
+    int[] dy = { 1, -1, 0, 0 };
+    boolean[][] visited;
+    public int[] solution(String[] maps) {
+        height = maps.length;
+        width = maps[0].length();
+        visited = new boolean[height][width];
+        
+        int food = 0;
+        List<Integer> land = new ArrayList<>();
+        for (int i=0; i<height; i++) {
+           	for (int j=0; j<width; j++) {
+                if (maps[i].charAt(j) == 'X' || visited[i][j]) continue;
+                food = bfs(i, j, maps);
+                land.add(food);
+            } 
+        }
+        
+        if (land.isEmpty()) {
+            return new int[] {-1};
+        } 
+        
+        Collections.sort(land);
+        int n = land.size();
+        int[] answer = new int[n];
+        for (int i=0; i<n; i++) {
+            answer[i] = land.get(i); 
+        }	
+
+        return answer;
+    }
+    public int bfs(int y, int x, String[] maps) {
+       	Queue<int[]> queue = new LinkedList<>();
+        queue.offer(new int[] {x, y});
+        visited[y][x] = true;
+        
+        int food = 0;
+        while (!queue.isEmpty()) {
+            int[] curr = queue.poll();
+            int cx = curr[0];
+            int cy = curr[1];
+         
+            food += maps[cy].charAt(cx) - '0';
+            
+            for (int i=0; i<4; i++) {
+                int nx = cx + dx[i];
+                int ny = cy + dy[i];
+                
+                if (nx >= 0 && nx < width && ny >=0 && ny < height) {
+                    if (maps[ny].charAt(nx) != 'X' && !visited[ny][nx]) {
+                        visited[ny][nx] = true;
+                        queue.offer(new int[] {nx, ny});
+                    }
+                }
+            }
+        }
+       	return food; 
+    }
+}