[Error] invalid types 'int[int]' for array subscript

Question

12 14 D:\MC\C++\main.cpp [Error] invalid types 'int[int]' for array subscript这个问题咋解决啊
代码在下：

#include<bits/stdc++.h>
using namespace std;
int a[1000000001];
int main(){
    int n;
    cin >> n;
    int sum = 0;
    for(int i = 0;i < n;i ++){
        int a,b,c,r;
        cin >> a >> b >> c >> r;
        for(int j = 0;j < 1000;j ++){
            a[j] = 1;                      //报错位置
        }
        for(int j = c - r + 100;j <= c + r;j ++){
             a[j] = 0;
        }
        for(int j = a + 100;j <= b + 100;j ++){
             sum += a[j];
        }
    }
    cout << sum;
}

Answer 1

#include <iostream>
using namespace std;
int aa[1000000];
int main(){
    int n;
    cin >> n;
    int sum = 0;
    for(int i = 0;i < n;i ++){
        int a,b,c,r;
        cin >> a >> b >> c >> r;
        for(int j = 0;j < 1000;j ++){
            aa[j] = 1;                      //报错位置
        }
        for(int j = c - r + 100;j <= c + r;j ++){
             aa[j] = 0;
        }
        for(int j = a + 100;j <= b + 100;j ++){
             sum += aa[j];
        }
    }
    cout << sum;
    return 0;
}