[백준][Java] 11659번 구간 합 구하기 4 (누적합)

수행 시간 낮춰주려면

Line:30부분의 출력 부분을 

 

(X)

for(i=1; i<=M; i++) {
     str = br.readLine().split(" ");
     System.out.println(accum[Integer.parseInt(str[1])] - accum[Integer.parseInt(str[0])-1]);
} 

 

(O)

StringBuilder sBuilder = new StringBuilder();

        for(i=1; i<=M; i++) {

            str = br.readLine().split(" ");

            sBuilder.append(accum[Integer.parseInt(str[1])] - accum[Integer.parseInt(str[0])-1]+"\n");

        }

        System.out.println(sBuilder.toString());

 

로 바꿔주면 된다 1줄에 한번씩 system call하면 시간 2배로 걸림

 

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.StringTokenizer;
 
 
public class Main {
        
    private static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    private static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
    
    
    public static void main(String[] args) throws IOException{
        String[] str = br.readLine().split(" ");
        int N = Integer.parseInt(str[0]);
        int M = Integer.parseInt(str[1]);
        int[] num = new int[N+1];
        int[] accum = new int[N+1];
        
        StringTokenizer stk = new StringTokenizer(br.readLine()," ");
        int i=1;
        while(stk.hasMoreTokens()) {
            num[i] = Integer.parseInt(stk.nextToken());
            accum[i] = accum[i-1] + num[i];
            i++;
        }
        
        StringBuilder sBuilder = new StringBuilder();
        for(i=1; i<=M; i++) {
            str = br.readLine().split(" ");
            sBuilder.append(accum[Integer.parseInt(str[1])] - accum[Integer.parseInt(str[0])-1]+"\n");
        }
        System.out.println(sBuilder.toString());
        
        
//        bw.write("");
//        bw.flush(); 
//        bw.close();
    }
}