题目描述

仅供参考

算法1

用总面积减去重复面积

Java 代码

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

public class Main {
    static int N = 110;
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        int [][] arr = new int[N][N];
        boolean [][] flag = new boolean[N][N];
        for(int i = 0 ; i < n ;i++){
            String[] s = br.readLine().split(" ");
            for(int j = 0  ;j < 4;j++){
                arr[i][j] = Integer.parseInt(s[j]);
            }
        }
        int sum = 0;
        for(int i = 0 ; i< n;i++){
            int x1 = arr[i][0], y1 = arr[i][1];
            int x2 = arr[i][2], y2 = arr[i][3];
            sum += (x2 - x1) * (y2 - y1);

            for(int j=x1; j<x2; j++) {
                for(int k=y1; k<y2; k++) {
                    if(flag[j][k]) {
                        sum--;
                    }
                    flag[j][k] = true;
                }
            }
        }
        System.out.println(sum);

算法2

先标记 再统计

Java 代码

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

public class Main {
    static int N = 110;
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        int [][] arr = new int[N][N];
        boolean [][] flag = new boolean[N][N];
        for(int i = 0 ; i < n ;i++){
            String[] s = br.readLine().split(" ");
            for(int j = 0  ;j < 4;j++){
                arr[i][j] = Integer.parseInt(s[j]);
            }
        }
          int sum = 0;
        for(int i = 0 ; i< n;i++) {
            int x1 = arr[i][0], y1 = arr[i][1];
            int x2 = arr[i][2], y2 = arr[i][3];
            for(int j=x1; j<x2; j++) {
                for(int k=y1; k<y2; k++) {
                    flag[j][k] = true;
                }
            }
        }
        for(int i=  0 ;i<=100 ;i++){
            for(int j = 0 ;j <=100 ;j++){
                sum+= flag[i][j] ? 1 : 0;
            }
        }

        System.out.println(sum);
    }
}

算法2

在标记的同时统计
193ms,我提交的代码中最快的一次

Java 代码

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

public class Main {
    static int N = 110;
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        int [][] arr = new int[N][N];
        boolean [][] flag = new boolean[N][N];
        for(int i = 0 ; i < n ;i++){
            String[] s = br.readLine().split(" ");
            for(int j = 0  ;j < 4;j++){
                arr[i][j] = Integer.parseInt(s[j]);
            }
        }

        int sum = 0;
        for(int i = 0 ; i< n;i++) {
            int x1 = arr[i][0], y1 = arr[i][1];
            int x2 = arr[i][2], y2 = arr[i][3];
            for(int j=x1; j<x2; j++) {
                for(int k=y1; k<y2; k++) {
                    if (!flag[j][k]){
                        sum++;
                        flag[j][k] = true;
                    }
                }
            }
        }
        System.out.println(sum);
    }
}