백준[Java] 8393번 합 (*문제는 쉽지만 시간초과에 대한 문제! 중요!)

https://www.acmicpc.net/problem/15552

15552번: 빠른 A+B

문제의 어려운 점

1. 시간제한은 1.5초 즉 1500ms 이내
2. Scanner 사용시 시간초과
3. System.out.printn 시간초과

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문제풀이 1
BufferedWriter 사용

// BufferedWriter
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 _15552_1 {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int T = Integer.parseInt(br.readLine());

        StringTokenizer st;

        for (int i = 0; i < T; i++) {
            st = new StringTokenizer(br.readLine(), " ");
            bw.write(Integer.parseInt(st.nextToken()) + Integer.parseInt(st.nextToken()) + "\n");
        }
        br.close();
        bw.flush();
        bw.close();
    }
}

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문제풀이 2
StringBuilder 사용

// StringBuilder
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.StringTokenizer;

public class _15552_2 {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int T = Integer.parseInt(br.readLine());

        StringTokenizer st;
        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < T; i++) {
            st = new StringTokenizer(br.readLine(), " ");
            sb.append(Integer.parseInt(st.nextToken()) + Integer.parseInt(st.nextToken())).append("\n");
        }
        br.close();

        System.out.println(sb);

    }
}

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문제풀이 3

// BufferedWriter
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 _15552_3 {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        StringTokenizer st;
        int T = Integer.parseInt(br.readLine());

        for(int i=0; i<T; i++) {
            st = new StringTokenizer(br.readLine());
            int A = Integer.parseInt(st.nextToken());
            int B = Integer.parseInt(st.nextToken());
            int sum = A+B;

            bw.write(sum + "\n");
        }
        bw.flush();

    }
}

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문제풀이 4
시간단축 제일 빨리됨

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

public class _15552_4 {
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int T = Integer.parseInt(br.readLine());

        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < T; i++) {
            String str = br.readLine();
            int target = str.indexOf(" ");
            int result = Integer.parseInt(str.substring(0, target)) + Integer.parseInt(str.substring(target + 1));
            sb.append(result + "\n");
        }
        br.close();
        System.out.print(sb);
    }
}

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