C++ 向量和数组

Question

I was trying to solve a HackerRank question named "Array Manipulation" The link of the problem . I wrote this code below. It works fine. However, when I use an array instead of vector I got segmentation fault at case 7-13. Why did it happen?

long arrayManipulation(int n, vector<vector<int>> queries) {
    vector<long> arr(n);
    long sum=0, max=LONG_MIN;
    for(int i=0;i<n;i++){
        arr[i] = 0;
    }
    for(int i=0;i<queries.size();i++){
        arr[queries[i][0]-1] += queries[i][2];
        if(queries[i][1]<n) arr[queries[i][1]] -= queries[i][2];
    }
    for(int i=0;i<n;i++){
        sum += arr[i];
        if(sum>max) max=sum;
    }
    return max; }

long arrayManipulation(int n, vector<vector<int>> queries) {
    long arr[n];
    long sum=0, max=LONG_MIN;
    for(int i=0;i<n;i++){
        arr[i]=0;
    }
    for(int i=0;i<queries.size();i++){
        arr[queries[i][0]-1]+=queries[i][2];
        if(queries[i][1]<n) arr[queries[i][1]]-=queries[i][2];
    }
    for(int i=0;i<n;i++){
        sum+=arr[i];
        if(sum>max) max=sum;
    }
    return max;
}

Answer 1

Variable length arrays have a limit of available stack limit, if it surpasses the limit SegV (by stack overflow) can occur.

The same can happen for fixed length array if size is large enough.

Try with this to see the issue:

long arr[10000000];  // should fail for same reason in HackerRank