나호균 / 10월 1주차 / 목

[nahokyun]

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🎈boj 2660 - 회장뽑기

🗨 해결방법 : bfs

📝메모 :

✔코드 :

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collections;
import java.util.StringTokenizer;

public class Main {

	private static Node[] relation;
	private static int n;

	public static void main(String[] args) throws NumberFormatException, IOException {
		// TODO Auto-generated method stub
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		n = Integer.parseInt(br.readLine());
		relation = new Node[n + 1];

		for (int i = 1; i <= n; i++) {
			relation[i] = new Node(null, i);
		}

		while (true) {
			StringTokenizer st = new StringTokenizer(br.readLine());
			int first = Integer.parseInt(st.nextToken());
			int second = Integer.parseInt(st.nextToken());

			if (first == -1 && second == -1) {
				break;
			}

			relation[first].next = new Node(relation[first].next, second);
			relation[second].next = new Node(relation[second].next, first);
		}
		// 입력 종료

		int[] score = new int[n + 1];
		for (int i = 1; i <= n; i++) {
			score[i] = bfs(i);
		}

		ArrayList<Integer> al = new ArrayList<>();
		int min = n+2;
		for (int i = 1; i <= n; i++) {
			if (score[i] < min) {
				al.clear();
				al.add(i);
				min = score[i];
			} else if (score[i] == min) {
				al.add(i);
			}
		}
		
		Collections.sort(al);
		StringBuilder sb = new StringBuilder();
		sb.append(min-1).append(" ").append(al.size()).append("\n");
		for (int i : al) {
			sb.append(i).append(" ");
		}

		System.out.println(sb.toString());
	}

	private static int bfs(int i) {
		ArrayDeque<Integer> q = new ArrayDeque<>();
		q.add(i);
		boolean[] visited = new boolean[n + 1];
		visited[i] = true;
		int depth = 0;
		while (!q.isEmpty()) {
			ArrayDeque<Integer> tmp = new ArrayDeque<>();
			
			while (!q.isEmpty()) {
				int cur = q.poll();

				for (Node next = relation[cur].next; next != null; next = next.next) {
					if (!visited[next.num]) {
						tmp.add(next.num);
						visited[next.num] = true;
					}
				}

			}
			depth++;
			q = tmp;
		}

		return depth;
	}

	static class Node {
		Node next;
		int num;

		public Node(Node next, int num) {
			super();
			this.next = next;
			this.num = num;
		}
	}
}

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🎈boj 15817 - 배수 공사

🗨 해결방법 : 배낭

📝메모 :

✔코드 :

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());

		int n = Integer.parseInt(st.nextToken());
		int x = Integer.parseInt(st.nextToken());

		Pipe[] pipes = new Pipe[n+1];
		int[][] dp = new int[n+1][x + 1];

		for (int i = 1; i <= n; i++) {
			st = new StringTokenizer(br.readLine());
			int l = Integer.parseInt(st.nextToken());
			int c = Integer.parseInt(st.nextToken());

			pipes[i] = new Pipe(l, c);

		}
		// 입력 종료
		

		dp[0][0]=1;
		for (int i = 1; i <= n; i++) {
			int curLength=pipes[i].length;
			for (int j = 0; j <= x; j++) {
				if(j==0) {
					dp[i][j]=1;
					continue;
				}
				if(j<curLength) {
					dp[i][j]=dp[i-1][j];
					continue;
				}
				for (int count = 0; count <= pipes[i].quantity; count++) {
					if (j >= count * curLength) {
						dp[i][j]+=dp[i-1][j-curLength*count];
					}
				}
			}
		}
		
		
		
		System.out.println(dp[n][x]);
	}

	static class Pipe {
		int length;
		int quantity;

		public Pipe(int length, int quantity) {
			super();
			this.length = length;
			this.quantity = quantity;
		}

	}

}

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🎈boj 18427 - 함께 블록 쌓기

🗨 해결방법 : 배낭

📝메모 :

✔코드 :

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		StringTokenizer st = new StringTokenizer(br.readLine());

		int n = Integer.parseInt(st.nextToken());
		int m = Integer.parseInt(st.nextToken());
		int h = Integer.parseInt(st.nextToken());

		int[][] dp = new int[n + 1][h + 1];
		ArrayList<Integer>[] al=new ArrayList[n+1];
		

		for (int i = 1; i <= n; i++) {
			al[i]=new ArrayList<>();
			st=new StringTokenizer(br.readLine());
			while(st.hasMoreTokens()) {
				al[i].add(Integer.parseInt(st.nextToken()));
			}
			
			
			al[i].add(0);
		}
		// 입력 종료
		dp[0][0] = 1;

		for (int i = 1; i <= n; i++) {
			dp[i][0]=1;
			for (int k = 1; k <= h; k++) {
				int tmp = 0;
				for (int j = 0; j < al[i].size(); j++) {
					int cur = al[i].get(j);
					
					if(cur<=k){
						tmp+=dp[i-1][k-cur]%10007;
					}

				}
				dp[i][k] = tmp%10007;
			}
		}

		System.out.println(dp[n][h]);

	}

}

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🎈boj 14699 - 관악산 등산

🗨 해결방법 : DP

📝메모 :

✔코드 :

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.StringTokenizer;

public class Main {

    private static Node[] nodes;
    private static int[] dp;

    public static void main(String[] args) throws IOException {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st=new StringTokenizer(br.readLine());

        int n=Integer.parseInt(st.nextToken());
        int m=Integer.parseInt(st.nextToken());

        st=new StringTokenizer(br.readLine());

        ArrayList<Pair> breakPoint=new ArrayList<>();
        dp = new int[n+1];

        for(int i=1;i<=n;i++){
            breakPoint.add(new Pair(Integer.parseInt(st.nextToken()),i));
        }

        nodes = new Node[n+1];
        for(int i=1;i<=n;i++){
            nodes[i]=new Node(null,i);
        }


        for(int i=0;i<m;i++){
            st=new StringTokenizer(br.readLine());

            int first=Integer.parseInt(st.nextToken());
            int second=Integer.parseInt(st.nextToken());

            nodes[first].next=new Node(nodes[first].next,second);
            nodes[second].next=new Node(nodes[second].next,first);
        }

        Collections.sort(breakPoint);

        for(Pair cur:breakPoint){
            find(cur.num);
        }

        StringBuilder sb=new StringBuilder();
        for(int i=1;i<=n;i++){
            sb.append(dp[i]).append('\n');
        }
        System.out.println(sb);

    }
    private static void find(int cur){
        int max=0;
        for(Node next=nodes[cur].next;next!=null;next=next.next){
            if(dp[next.num]>max){
                max=dp[next.num];
            }
        }

        dp[cur]=max+1;

    }

    static class Pair implements Comparable<Pair>{
        int height;
        int num;

        public Pair(int height, int num) {
            this.height = height;
            this.num = num;
        }

        @Override
        public int compareTo(Pair o) {
            return o.height-this.height;
        }
    }


    static class Node{
        Node next;
        int num;

        public Node(Node next, int num) {
            this.next = next;
            this.num = num;
        }
    }
}

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🎈boj 17404 - RGB거리 2

🗨 해결방법 : 첫 출발지점을 고려한 dp

📝메모 :

✔코드 :

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {

    public static void main(String[] args) throws NumberFormatException, IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());

        int[][] colors = new int[n][3];
        int[][] dp = new int[n][3];
        for (int i = 0; i < n; i++) {
            StringTokenizer st = new StringTokenizer(br.readLine());
            for (int j = 0; j < 3; j++) {
                colors[i][j] = Integer.parseInt(st.nextToken());
            }
        }
        //입력 종료
        

        int result=10000000;
        for(int c=0;c<3;c++) {
            for(int i=0;i<3;i++){
                dp[0][i]=i==c?colors[0][i]:10000;
            }

            for (int i = 1; i < n; i++) {
                dp[i][0] = (Math.min(dp[i - 1][1], dp[i - 1][2])) + colors[i][0];
                dp[i][1] = (Math.min(dp[i - 1][0], dp[i - 1][2])) + colors[i][1];
                dp[i][2] = (Math.min(dp[i - 1][0], dp[i - 1][1])) + colors[i][2];
            }

            for(int i = 0 ; i < 3; i++)
                if(i != c)
                    result = Math.min(result, dp[n-1][i]);
        }
        System.out.println(result);

    }
}

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🎈boj 1300 - K번째 수

🗨 해결방법 : 이분탐색

📝메모 : 접근할때 이분탐색을 생각하지 못했음

✔코드 :

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	private static long n;
	private static long k;

	public static void main(String[] args) throws NumberFormatException, IOException {
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		
		n = Integer.parseInt(br.readLine());
		k = Integer.parseInt(br.readLine());

		long left=0;
		long right=n*n;
		long mid=0;
		
		while(left+1<right) {
			mid=(left+right)>>1;
		
			if(check(mid)) {
				left=mid;
			}else {
				right=mid;
			}
		}
		System.out.println(right);
		
	}

	private static boolean check(long mid) {
		long count=0;
		
		for(long i=1;i<=n;i++) {
			count+=mid/i>=n?n:mid/i;
			
			if(count>=k) {//수가 많으면 false 리턴 =>수를 줄여야함
				return false;
			}
		}
		
		
		return count>=k?false:true;
	}

}