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int InversePairs(int* data, int length){    if(data == NULL || length < 0)        return 0;    int* copy = new int[length];    for(int i = 0; i < length; ++ i)        copy[i] = data[i];    int count = InversePairsCore(data, copy, 0, length - 1);    delete[] copy;    return count;}int InversePairsCore(int* data, int* copy, int start, int end){    if(start == end)    {        copy[start] = data[start];        return 0;    }    int length = (end - start) / 2;    int left = InversePairsCore(copy, data, start, start + length);    int right = InversePairsCore(copy, data, start + length + 1, end);    // i初始化为前半段最后一个数字的下标    int i = start + length;     // j初始化为后半段最后一个数字的下标    int j = end;     int indexCopy = end;    int count = 0;    while(i >= start && j >= start + length + 1)    {        if(data[i] > data[j])        {            copy[indexCopy--] = data[i--];            count += j - start - length;        }        else        {            copy[indexCopy--] = data[j--];        }    }    for(; i >= start; --i)        copy[indexCopy--] = data[i];    for(; j >= start + length + 1; --j)        copy[indexCopy--] = data[j];    return left + right + count;}