[BOJ/JAVA] 백준 1351번 : 무한 수열

1351번: 무한 수열

 

 

 

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• 풀이

 

처음엔 재귀형식으로 풀어보려했지만 시간초과가 떴습니다. 

 

다음 dp를 통해 풀어보려 했지만 N의 최대값이 너무 크기때문에 배열을 만들 수 없었습니다. 그래서 Map을 통해 dp배열처럼 사용했습니다. 

 

 

 

• 코드

 

import java.io.IOException;
import java.io.InputStream;
import java.util.*;

public class Main {
	static long N, answer;
	static int P, Q;
	static Map<Long, Long> map;
	
	public static void main(String[] args) throws Exception {
		SetData();
		System.out.println(answer);
	}

	// 데이터
	private static void SetData() throws Exception {
		InputReader in = new InputReader(System.in);
		
		N = in.nextLong();
		P = in.nextInt();
		Q = in.nextInt();
		answer = 0;
		map = new HashMap<>();
		
		answer = recursion(N);
	}
	
	private static long recursion(long value) {
		if(value == 0) return 1;
		if(map.containsKey(value)) return map.get(value);
		
		map.put(value, recursion(value/P) + recursion(value/Q));
		return map.get(value);
	}
}

class InputReader {
	private final InputStream stream;
	private final byte[] buf = new byte[8192];
	private int curChar, snumChars;

	public InputReader(InputStream st) {
		this.stream = st;
	}

	public int read() {
		if (snumChars == -1)
			throw new InputMismatchException();
		if (curChar >= snumChars) {
			curChar = 0;
			try {
				snumChars = stream.read(buf);
			} catch (IOException e) {
				throw new InputMismatchException();
			}
			if (snumChars <= 0)
				return -1;
		}
		return buf[curChar++];
	}

	public int nextInt() {
		int c = read();
		while (isSpaceChar(c)) {
			c = read();
		}
		int sgn = 1;
		if (c == '-') {
			sgn = -1;
			c = read();
		}
		int res = 0;
		do {
			res *= 10;
			res += c - '0';
			c = read();
		} while (!isSpaceChar(c));
		return res * sgn;
	}

	public long nextLong() {
		int c = read();
		while (isSpaceChar(c)) {
			c = read();
		}
		int sgn = 1;
		if (c == '-') {
			sgn = -1;
			c = read();
		}
		long res = 0;
		do {
			res *= 10;
			res += c - '0';
			c = read();
		} while (!isSpaceChar(c));
		return res * sgn;
	}

	public int[] nextIntArray(int n) {
		int a[] = new int[n];
		for (int i = 0; i < n; i++) {
			a[i] = nextInt();
		}
		return a;
	}

	public String nextLine() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		StringBuilder res = new StringBuilder();
		do {
			res.appendCodePoint(c);
			c = read();
		} while (!isEndOfLine(c));
		return res.toString();
	}

	public boolean isSpaceChar(int c) {
		return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	}

	private boolean isEndOfLine(int c) {
		return c == '\n' || c == '\r' || c == -1;
	}
}