#11660: 구간 합 구하기 5 [JAVA]

https://www.acmicpc.net/problem/11660

11660번: 구간 합 구하기 5

 

 

 

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문제 접근

 

 

 

1. 행 별로 메모제이션 해서 구할 수 있음(#11659 구간 합 4 아이디어)

 

2. 2차원으로 메모제이션 해서 구할 수 있음

 

 

 

 

 

 

[ 참고 ] https://propercoding.tistory.com/29

 

 

 

 

 

 

 

 

 

코드

 

 

 

 

1. 

 

 

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class Main {

	static StringBuilder sb;

	public static void main(String[] args) throws IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		StringBuilder sb=new StringBuilder();

		int n = Integer.parseInt(st.nextToken());
		int m = Integer.parseInt(st.nextToken());

		int[][] arr = new int[n + 1][n + 1];

		for (int i = 1; i <= n; i++) {
			st = new StringTokenizer(br.readLine());
			for (int j = 1; j <= n; j++) {
				arr[i][j] = arr[i][j - 1] + Integer.parseInt(st.nextToken());
			}
		}

		while (m-- > 0) {
			int result = 0;

			st = new StringTokenizer(br.readLine());
			int x1 = Integer.parseInt(st.nextToken());
			int y1 = Integer.parseInt(st.nextToken());
			int x2 = Integer.parseInt(st.nextToken());
			int y2 = Integer.parseInt(st.nextToken());

			for (int i = x1; i <= x2; i++) {
				result += arr[i][y2] - arr[i][(y1 - 1)];
			}

			sb.append(result).append("\n");
		}
		System.out.println(sb);

	}

}

 

 

 

 

StringBuilder 안쓰고 그냥 바로 출력하니까 시간 초과 났다.

 

 

 

 

 

 

 

2.

 

 

 

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class Main {

	static StringBuilder sb;

	public static void main(String[] args) throws IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		StringBuilder sb=new StringBuilder();

		int n = Integer.parseInt(st.nextToken());
		int m = Integer.parseInt(st.nextToken());

		int[][] arr = new int[n + 1][n + 1];

		for (int i = 1; i <= n; i++) {
			st = new StringTokenizer(br.readLine());
			for (int j = 1; j <= n; j++) {
				arr[i][j] = arr[i][j - 1] + arr[i-1][j] -arr[i-1][j-1] + Integer.parseInt(st.nextToken());
			}
		}

		while (m-- > 0) {
			int result = 0;

			st = new StringTokenizer(br.readLine());
			int x1 = Integer.parseInt(st.nextToken());
			int y1 = Integer.parseInt(st.nextToken());
			int x2 = Integer.parseInt(st.nextToken());
			int y2 = Integer.parseInt(st.nextToken());

			result=arr[x2][y2]-arr[x2][y1-1]-arr[x1-1][y2]+arr[x1-1][y1-1];

			sb.append(result).append("\n");
		}
		System.out.println(sb);

	}

}

 

 

 

 

성능은 2가 훨씬 좋다