[6주차] 배수빈

BOJ/1000-5000번/SB_2110.java

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+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+public class SB_2110 {
+    static int N, C;
+    static int[] house;
+
+    private static boolean canWifi(int dist) {
+        int cnt = 1;
+        int pre = house[0];
+        for (int i = 1; i < N; i++) {
+            if (house[i]-pre >= dist){
+                cnt++;
+                pre = house[i];
+            }
+            if (cnt >=C) return true;
+        }
+        return false;
+    }
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        N = Integer.parseInt(st.nextToken());
+        C = Integer.parseInt(st.nextToken());
+
+        house = new int[N];
+        for (int i = 0; i < N; i++) {
+            house[i] = Integer.parseInt(br.readLine());
+        }
+        Arrays.sort(house);
+
+        // 거리: mid, 공유기 개수: C (조건)
+        int s = 1;
+        int e = house[N-1] - house[0];
+        int parm = 0;
+        while (s <= e) {
+            int mid = (s + e) / 2;
+            if (canWifi(mid)) {     // 공유기 가능하면 거리 더 늘려보기
+                parm = mid;
+                s = mid+1;
+            }else e = mid-1;
+        }
+        System.out.println(parm);
+    }
+}

BOJ/1000-5000번/SB_2805.java

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+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+public class SB_2805 {
+    static int N, M;
+    static int[] trees;
+
+    // 파라미터 서치: 잘린 길이가 M보다 크거나 같은가
+    // 높이 최대값: mid변수
+    private static boolean canGet(int idx, int h) {
+        long cnt = 0;
+        for (int i = idx; i < N; i++) {
+            cnt += trees[i]-h;
+            if (cnt>=M) return true;
+        }
+        return cnt>=M;
+    }
+
+    private static int findIdx(int h) {     // 얘도 upper-bound로 인덱스 위치 찾기
+        int left = 0;
+        int right = N;                     // upper-bound시 탐색범위는 [0,N)
+        while (left < right){
+            int mid = (left+right)/2;
+            if (trees[mid] <= h) left = mid+1;
+            else right = mid;
+        }
+        return left;
+    }
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+
+        trees = new int[N];
+        st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < N; i++) {
+            trees[i] = Integer.parseInt(st.nextToken());
+        }
+
+        Arrays.sort(trees);
+
+        int left = 0;   // 절단기 높이값이 작을 수록 많이 자름
+        int right = trees[N-1];
+        int parm = 0;
+
+        while (left <= right){       // 절단기 높이의 최대값이므로 upper-bound
+            int height = (left+right)/2;
+            int idx = findIdx(height);
+            if (canGet(idx, height)) {
+                parm = height;
+                left = height+1;      // 나무 얻을 수 있으면 높이 조금 더 높여보기
+            }
+            else right = height-1;
+        }
+        System.out.println(parm);
+    }
+}

BOJ/5001-10000번/SB_7579.java

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+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+public class SB_7579 {
+    static int N, M;
+    static int[] memo, cost;
+
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+
+        memo = new int[N];
+        cost = new int[N];
+
+        st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < N; i++) {
+            memo[i] = Integer.parseInt(st.nextToken());
+        }
+
+        st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < N; i++) {
+            cost[i] = Integer.parseInt(st.nextToken());
+        }
+
+        // 비활성화 비용 최소화로 M바이트 확보
+        int[] dp = new int[10001];
+
+        // dp[i] = j : i비용으로 얻을 수 있는 최대 메모리 j
+        for (int i = 0; i <N; i++) {                // 앱 번호
+            for (int j = 10000; j >=cost[i]; j--) {         // 비용
+                dp[j] = Math.max(dp[j], dp[j - cost[i]] + memo[i]);
+            }
+        }
+
+        int ans = 0;
+        for (int i = 0; i <= 10000; i++) {
+            if (dp[i] >=M) {
+                ans = i;
+                break;
+            }
+        }
+        System.out.println(ans);
+    }
+}

BOJ/5001-10000번/SB_9084.java

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+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+public class SB_9084 {
+    private static int calMethod(int N, int[] coin, int M) {
+        int[] dp = new int[M + 1];
+        dp[0] = 1;
+
+        for (int c : coin) {
+            for (int i = c; i <= M; i++) {
+                dp[i] += dp[i - c];
+            }
+        }
+        return dp[M];
+    }
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st;
+        StringBuilder sb = new StringBuilder();
+
+        int T = Integer.parseInt(br.readLine());
+
+        while (T-- > 0) {
+            int N = Integer.parseInt(br.readLine());
+            int[] coin = new int[N];
+            st = new StringTokenizer(br.readLine());
+            for (int i = 0; i < N; i++) {
+                coin[i] = Integer.parseInt(st.nextToken());
+            }
+            int M = Integer.parseInt(br.readLine());
+
+            sb.append(calMethod(N, coin, M)).append('\n');
+        }
+        System.out.println(sb);
+    }
+}

CodeTree/2017-2018년/SB_테트리스_블럭_안의_합_최대화_하기.java

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+import java.io.*;
+import java.util.*;
+
+public class SB_테트리스_블럭_안의_합_최대화_하기 {
+    static int N,M;
+    static int[][] board;
+    static boolean[][] visited;
+    static int mx = 0;
+    static int[] dx = {-1, 1, 0, 0};
+    static int[] dy = {0, 0, -1, 1};
+
+    private static void dfs(int x, int y, int depth, int total) {
+        // if (mx > mx*(4-depth)+total) return;
+        if(depth==4){
+            mx = Math.max(mx, total);
+            return;
+        }
+
+        for (int i = 0; i < 4; i++) {
+            int nx = x+dx[i];
+            int ny = y+dy[i];
+            if (!isValid(nx, ny) || visited[nx][ny]) continue;
+            if (depth == 2) {
+                visited[nx][ny] = true;
+                dfs(x, y, depth+1, total+board[nx][ny]);        // ㅜ 가 갈라지는 중점에서 양옆 탐색
+                visited[nx][ny] = false;
+            }
+            visited[nx][ny] = true;
+            dfs(nx, ny, depth+1, total+board[nx][ny]);
+            visited[nx][ny] = false;
+        }
+    }
+
+    private static boolean isValid(int x, int y) {
+        return 0<=x && x<N && 0<=y && y<M;
+    }
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+
+        board = new int[N][M];
+        visited = new boolean[N][M];
+        for(int i=0; i<N; i++){
+            st = new StringTokenizer(br.readLine());
+            for (int j = 0; j < M; j++) {
+                board[i][j] = Integer.parseInt(st.nextToken());
+            }
+        }
+
+        for (int i = 0; i < N; i++) {
+            for (int j = 0; j < M; j++) {
+                visited[i][j] = true;
+                dfs(i, j, 1, board[i][j]);
+                visited[i][j] = false;
+            }
+        }
+        System.out.println(mx);
+    }
+}

Programmers/Level3/SB_42861.java

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+import java.util.Arrays;
+
+class Solution {
+    static int[] parents;
+
+    private static int find(int x) {
+        if (parents[x] != x) {
+            return find(parents[x]);
+        }
+        return parents[x];
+    }
+
+    private static void union(int a, int b) {
+        if (a > b) parents[b] = a;
+        else parents[a] = b;
+    }
+    public static int solution(int n, int[][] costs) {
+        Arrays.sort(costs, (o1, o2)->{
+            return o1[2]-o2[2];
+        });
+
+        parents = new int[n];
+        for (int i = 0; i < n; i++) {
+            parents[i] = i;
+        }
+
+        int cnt = 1;
+        int ans = 0;
+        for (int[] cur : costs) {
+            if (cnt==n) break;
+            int p_a = find(cur[0]);
+            int p_b = find(cur[1]);
+
+            if (p_a != p_b) {
+                union(p_a, p_b);
+                ans+=cur[2];
+                cnt++;
+            }
+        }
+        return ans;
+    }
+}

Programmers/Level3/SB_43238.java

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+import java.util.*;
+
+class Solution {
+    private static boolean canCheck(long target, int[] times, int n) {
+        long cnt = 0;
+        for (int tm : times) {
+            cnt += target / tm;
+            if (cnt >= n) return true;
+        }
+        return false;
+    }
+    public static long solution(int n, int[] times) {
+        Arrays.sort(times);
+
+        // 매개변수 탐색, 주어진 시간 내 n명 이상의 사람 처리할 수 있는지
+        long left = 0;
+        long right = (long) times[times.length - 1] * n;       // 최대 시간
+
+        long parm = 0;
+        while (left <= right) {
+            long mid = (left + right) / 2;
+            if (canCheck(mid, times, n)) {
+                parm = mid;
+                right = mid - 1;
+            } else {
+                left = mid + 1;
+            }
+        }
+        return parm;
+    }
+}

SQL/06주차/SB_Count Salary Categories.sql

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+# 각 급여 범주에 대한 은행 계좌 수를 계산
+# 결과표에는 세 가지 범주가 모두 포함되어야 합니다. 카테고리에 계정이 없으면 0 반환
+
+SELECT 'High Salary' AS category,
+    SUM(income > 50000) AS accounts_count
+FROM Accounts
+UNION
+SELECT 'Average Salary' AS category,
+    SUM(income BETWEEN 20000 AND 50000) AS accounts_count
+FROM Accounts
+UNION
+SELECT 'Low Salary' AS category,
+    SUM(income < 20000) AS accounts_count
+FROM Accounts

SQL/06주차/SB_Managers with at Least 5 Direct Reports.sql

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+# 최소 5명의 직속 부하 직원이 있는 관리자를 찾기
+
+SELECT e.name
+FROM Employee e
+JOIN Employee m ON e.id = m.managerId
+GROUP BY m.managerId
+HAVING COUNT(m.managerId) >=5;