简单的分情况讨论
import java.util.*;
public class Main{
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int n = input.nextInt();
int time =0;
int[][] h = new int[n][2];
int[][] w = new int[n][2];
for(int p =0;p<n;p++) {
h[p][0] = input.nextInt();
h[p][1] = input.nextInt();
}
for(int p =0;p<n;p++) {
w[p][0] = input.nextInt();
w[p][1] = input.nextInt();
}
input.close();
int i =0;
int j =0;
while(i<n&&j<n) {
int start_h = h[i][0];
int end_h = h[i][1];
int start_w = w[j][0];
int end_w = w[j][1];
// System.out.print(start_h+" "+end_h+" ");
// System.out.println(start_w+" "+end_w);
// 1
if(start_w >= start_h && start_w < end_h) {
if(end_w >= end_h) {
time += end_h-start_w;
i++;
continue;
}
if(end_w < end_h) {
time += end_w-start_w;
j++;
continue;
}
}
//2
if(start_h >= start_w && start_h < end_w) {
if(end_h >= end_w) {
time += end_w-start_h;
j++;
continue;
}
if(end_h < end_w) {
time += end_h-start_h;
i++;
continue;
}
}
if(start_h >= end_w) j++;
if(start_w >= end_h) i++;
//System.out.print(i+" "+j);
}
System.out.print(time);
}
}