只能过前一半，50分，求助

#include<stdio.h>
int merge(int *a,int *temp,int left,int c,int right){
    int i,j;
    long long n=0;
    int k=left;
    i=left,j=c+1;
    while(i<=c&&j<=right){
        if(a[i]>a[j]){
            temp[k++]=a[j++];
            n += c+1-i; 
        }
        else{
            temp[k++]=a[i++];
        }
    }
    while(i<=c) 
        temp[k++]=a[i++];
    while(j<=right)
        temp[k++]=a[j++];
    for(int i=left;i<=right;i++)
        a[i]=temp[i];
    return n;
}
int Nixudui(int *a,int *temp,int left,int right){
    long long n=0;
    int c;
    if(left==right)
        return 0;
    else{
        c = (left+right)/2;
        n += Nixudui(a,temp,left,c);
        n += Nixudui(a,temp,c+1,right);
        n += merge(a,temp,left,c,right);
        return n;   
    }
}
int main(){
    int n;
    long long num;
    scanf("%d",&n);
    int a[n],temp[n];
    for(int i=0;i<n;i++)
        scanf("%d",&a[i]);
    num=Nixudui(a,temp,0,n-1);
    printf("%lld",num); 
}