[1463번] 1로 만들기

다이나믹 프로그래밍 기초

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) {
        FastScanner sc = new FastScanner();
 
        int n = sc.nextInt();
        int[] dp = new int[n+1];
        dp[1]=0;
        for(int i=2;i<=n;i++){
            if(i%3==0){
                if(i%2==0){
                    dp[i] = Math.min(dp[i/2], Math.min(dp[i-1],dp[i/3]))+1;
                }else
                    dp[i] = Math.min(dp[i/3], dp[i-1])+1;
            }else if(i%2==0){
                dp[i] = Math.min(dp[i/2], dp[i-1])+1;
            }else{
                dp[i] = dp[i-1]+1;
            }
        }
        System.out.println(dp[n]);
    } 
}
 
class FastScanner {
    BufferedReader br;
    StringTokenizer st;
 
    public FastScanner() {
        br = new BufferedReader(new InputStreamReader(System.in));
    }
 
    String nextToken() {
        while (st == null || !st.hasMoreElements()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return st.nextToken();
    }
 
    int nextInt() {
        return Integer.parseInt(nextToken());
    }
 
    long nextLong() {
        return Long.parseLong(nextToken());
    }
 
    double nextDouble() {
        return Double.parseDouble(nextToken());
    }
 
    String nextLine() {
        String str = "";
        try {
            str = br.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return str;
    }
}