[20250306] BOJ / P5 / 분수 / 권혁준

Author: oncsr

khj20006/202503/06 BOJ P5 분수.md

@@ -0,0 +1,79 @@
+```java
+
+import java.util.*;
+import java.io.*;
+import java.math.BigInteger;
+
+
+class Main {
+	
+	// IO field
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st;
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static int nextInt() {return Integer.parseInt(st.nextToken());}
+	static long nextLong() {return Long.parseLong(st.nextToken());}
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+	
+	// Additional field
+
+	static long T, I, N;
+	static String A, B;
+	
+	public static void main(String[] args) throws Exception {
+		
+		T = Integer.parseInt(br.readLine());
+		while(T-- > 0) {
+			
+			ready();
+			solve();
+			
+		}
+	
+		bwEnd();
+		
+	}
+	
+	static void ready() throws Exception{
+		
+		nextLine();
+		A = st.nextToken();
+		B = st.nextToken();
+		
+		nextLine();
+		I = nextLong();
+		N = nextLong();
+		
+	}
+	
+	static void solve() throws Exception{
+		
+		BigInteger a = new BigInteger(A);
+		BigInteger b = new BigInteger(B);
+		a = a.mod(b);
+		
+		// a가 더 작으면
+		BigInteger t = power(new BigInteger("10"), I-1, b);
+		a = a.multiply(t).mod(b);
+		for(int i=0;i<N;i++) {
+			bw.write(a.multiply(new BigInteger("10")).divide(b).toString().charAt(0));
+			a = a.multiply(new BigInteger("10")).mod(b);
+		}
+		bw.write("\n");
+		
+	}
+	
+	static BigInteger power(BigInteger x, long p, BigInteger m) {
+		if(p == 0) return new BigInteger("1");
+		if(p == 1) return x.mod(m);
+		BigInteger half = power(x, p>>1, m).mod(m);
+		half = half.multiply(half).mod(m);
+		if(p%2 == 0) return half;
+		return half.multiply(x).mod(m);
+	}
+	
+}
+
+```