#include "iostream"
using namespace std;
int main ()
{
    int acount[10005],sum,N,i,L,M,num1,num2,j;
    cin >> N;
    while(N--){
        acount[10005] = {0},sum=0;
        cin >>L>> M;//L 代表马路的长度，M 代表区域的数目
        for(i=0; i<M; i++){
            cin >>num1>>num2;//num1,num2表示起始、终点
            for(j=num1; j<=num2; j++)
              acount[j]++;  
        } 
        for(i=0; i<=L; i++)
        if(acount[i]!=0) sum++;
        cout << L+1-sum << endl;
    }
    return 0;
}

这个我把数组定义在外面导致答案错了，下面这个我把数组定义在循环里面，答案就对了

#include "iostream"
using namespace std;
int main ()
{
    int N,i,L,M,num1,num2,j;
    cin >> N;
    while(N--){
        int acount[10005] = {0},sum=0;
        cin >>L>> M;//L 代表马路的长度，M 代表区域的数目
        for(i=0; i<M; i++){
            cin >>num1>>num2;//num1,num2表示起始、终点
            for(j=num1; j<=num2; j++)
              acount[j]++;  
        } 
        for(i=0; i<=L; i++)
        if(acount[i]!=0) sum++;
        cout << L+1-sum << endl;
    }
    return 0;
}

Expected                              |    Yours
15
                                  |    15
964
                                  |    332
58
                                  |    19
75
                                  |    13
12
                                  |    7
468
                                  |    7
1699
                                  |    7
62
                                  |    7
390
                                  |    7
17
                                  |    2
24
                                  |    2
5
                                  |    2
69
                                  |    2
52
                                  |    0
227
                                  |    0
147
                                  |    0
731
                                  |    0
8
                                  |    0
82
                                  |    0
这是答案错误的地方，还麻烦大家能够帮我找出问题。

是我糊涂了，感谢指出，谢谢！