Week29 Study

2022/[Week29 - Mix]/김주현/Q1987.java

@@ -0,0 +1,89 @@
+// 1987번 알파벳 (G4) [백트래킹]
+/*
+<문제 정보>
+ 1.
+
+<변수 범위>
+ 1.
+
+<프로그램 진행>
+ 1.
+
+<필요 함수>
+ 1.
+
+ */
+
+
+import java.io.*;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.StringTokenizer;
+
+public class Q1987 {
+    static int N;
+    static int M;
+    static int answer = -1;
+    static char[][] map;
+    static boolean[] visitedAlphabet = new boolean[26];
+
+    static int[][] DIR = {{1,0}, {0,1}, {-1,0}, {0,-1}};
+
+    public static void main(String args[]) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        StringBuilder sb = new StringBuilder();
+        StringTokenizer st;
+
+        // ******************** 입력 & 초기화 ********************
+        st = new StringTokenizer(br.readLine());
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+        map = new char[N][M];
+        for (int i=0; i<N; i++) {
+            map[i] = br.readLine().toCharArray();
+        }
+
+        // ******************** 메인 로직 ********************
+
+        visitedAlphabet[alphabetToIndex(map[0][0])] = true;
+        dfs(1,0,0);
+
+        // ******************** 정답 출력 ********************
+        sb.append(answer);
+        bw.write(sb.toString());
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    public static void dfs(int depth, int x, int y) {
+//        System.out.printf("[IN] depth : %d, x : %d, y : %d Alphabet : %c \n", depth, x, y, map[x][y]);
+        int nextX, nextY;
+        boolean inRange;
+        boolean hasPossibleRoad = false;
+        for (int[] d : DIR) {
+            nextX = x + d[0];
+            nextY = y + d[1];
+            inRange = nextX >= 0 && nextY >=0 && nextX < N && nextY < M;
+            if (inRange && !visitedAlphabet[alphabetToIndex(map[nextX][nextY])]) {
+                int alphabetIndex = alphabetToIndex(map[nextX][nextY]);
+                hasPossibleRoad = true;
+                visitedAlphabet[alphabetIndex] = true;
+                dfs(depth+1, nextX, nextY);
+                visitedAlphabet[alphabetIndex] = false;
+            }
+        }
+
+        if (!hasPossibleRoad) {
+            answer = Math.max(answer, depth);
+//            System.out.printf("[OUT - No Path] depth : %d, x : %d, y : %d Alphabet : %c \n", depth, x, y, map[x][y]);
+            return;
+        }
+//        System.out.printf("[OUT - All Searched] depth : %d, x : %d, y : %d Alphabet : %c \n", depth, x, y, map[x][y]);
+    }
+
+    public static int alphabetToIndex (char alphabet) {
+        return alphabet - 'A';
+    }
+}

2022/[Week29 - Mix]/김주현/Q2212.java

@@ -0,0 +1,60 @@
+// 2212번 센서 (G5) [정렬]
+/*
+<문제 정보>
+ 1.
+
+<변수 범위>
+ 1.
+
+<프로그램 진행>
+ 1.
+
+<필요 함수>
+ 1.
+
+ */
+
+
+import java.io.*;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.StringTokenizer;
+
+public class Q2212 {
+
+    public static void main(String args[]) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        StringBuilder sb = new StringBuilder();
+        StringTokenizer st;
+
+        // ******************** 입력 & 초기화 ********************
+        int N = Integer.parseInt(br.readLine());
+        int K = Integer.parseInt(br.readLine());
+        int[] sensors = new int[N];
+        st = new StringTokenizer(br.readLine());
+        for (int i=0; i<N; i++) {
+            sensors[i] = Integer.parseInt(st.nextToken());
+        }
+
+        // ******************** 메인 로직 ********************
+        Arrays.sort(sensors);
+        Integer[] diffs = new Integer[N-1];
+        for (int i=0; i<N-1; i++) {
+            diffs[i] = sensors[i+1] - sensors[i];
+        }
+
+        Arrays.sort(diffs, Collections.reverseOrder());
+        int coverage = sensors[N-1] - sensors[0];
+        for (int i=0; i<Math.min(K-1, N-1); i++) {
+            coverage -= diffs[i];
+        }
+
+        // ******************** 정답 출력 ********************
+        sb.append(coverage);
+        bw.write(sb.toString());
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+}

2022/[Week29 - Mix]/김주현/Q2668.java

@@ -0,0 +1,86 @@
+// 2668번 숫자 고르기 (G5) [그리디]
+/*
+<문제 정보>
+ 1.
+
+<변수 범위>
+ 1.
+
+<프로그램 진행>
+ 1.
+
+<필요 함수>
+ 1.
+
+ */
+
+
+import java.io.*;
+import java.util.*;
+
+public class Q2668 {
+    static int N;
+    static int[] arr;
+    static boolean[] visited;
+    static int answer = 0;
+
+    public static void main(String args[]) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        StringBuilder sb = new StringBuilder();
+        StringTokenizer st;
+
+        // ******************** 입력 & 초기화 ********************
+        N = Integer.parseInt(br.readLine());
+        arr = new int[N+1];
+        for (int i=1; i<=N; i++) {
+            arr[i] = Integer.parseInt(br.readLine());
+        }
+
+        // ******************** 메인 로직 ********************
+        visited = new boolean[N+1];
+        for (int i=1; i<=N; i++) {
+            if (!visited[i]) {
+                search(i);
+            }
+        }
+
+        // ******************** 정답 출력 ********************
+        sb.append(answer).append("\n");
+        for (int i=1; i<=N; i++) {
+            if (visited[i]) sb.append(i).append("\n");
+        }
+
+        bw.write(sb.toString());
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    public static void search (int n) {
+        int start = n;
+        int end = 0;
+        Set<Integer> visitList = new HashSet<>();
+        boolean isOriginalPoint = false;
+
+        while ( !isOriginalPoint ) {
+            end = arr[start];
+            if ( visited[end] || visitList.contains(end) ) break;
+            visitList.add(end);
+            if (end == n) {
+                isOriginalPoint = true;
+            } else if ( start == end) {
+                break;
+            } else {
+                start = end;
+            }
+        }
+
+        if (isOriginalPoint) {
+            answer += visitList.size();
+            for (int point : visitList) {
+                visited[point] = true;
+            }
+        }
+    }
+}