문제

풀이

x가 행 y가 열로 된 것 주의!

1. x,y 까지의 누적합 구해주기
2. x2,y2 까지의 누적합= x2,y2 - x2,y1-1 - x1-1,y2 + x1-1,y1-1

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코드

import java.io.*;
import java.util.*;

public class Main {
    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;

        st=new StringTokenizer(br.readLine());
        int n=Integer.parseInt(st.nextToken());
        int m=Integer.parseInt(st.nextToken());
        int[][] nums=new int[n+1][n+1];
        for(int i=1;i<n+1;i++){
            st=new StringTokenizer(br.readLine());
            for(int j=1;j<n+1;j++){
                nums[i][j]=Integer.parseInt(st.nextToken());
            }
        }
        int[][] sums=new int[n+1][n+1];
        sums[1][1]=nums[1][1];
        for(int i=1;i<n+1;i++){
            for(int j=1;j<n+1;j++){
                if(i==1&&j==1)continue;
                sums[i][j]=sums[i-1][j]+sums[i][j-1]-sums[i-1][j-1]+nums[i][j];
            }
        }
        while(m-->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());
            bw.write(sums[x2][y2]-sums[x2][y1-1]-sums[x1-1][y2]+sums[x1-1][y1-1]+"\n");
        }
        bw.flush();
    }
}

#누적합