找出最长的递增子序列的长度

Question

I've written some code in C that, given a sequence, should find the length of the longest increasing subsequence. However it always returns the length 4 when this is incorrect.

Here is my code so far:

int LIS(int* seq, int* temp_seq, int seq_size)  
{int i, j;

for(i=0; i<seq_size; i++);
{ 
  temp_seq[i]=0; 
}
  for(i=1; i<seq_size; i++);
  { 
     for(j=1; j<seq_size; j++)
     { 
       if (seq[i]<temp_seq[j])
       seq[i]=temp_seq[j];

       else if (seq[i]>temp_seq[j]) 
       seq[i]=temp_seq[j+1];
     } 
  }
 return(sizeof temp_seq);
}

What am I doing wrong?

Also I should note that the sequence lists all integers from 1 to n with no repeated numbers.

Answer 1

1. Returning wrong value. return(sizeof temp_seq); is a constant, the size of the pointer temp_seq . @eurythmia

2. The ; after for(i=0; i<seq_size; i++); is certainly not needed as that completes the loop. Same for for(i=1; i<seq_size; i++); .

3. The value of seq[0] is never tested nor saved in temp_seq .

4. Possible access passed end of array with seq[i]=temp_seq[j+1];

5. Code appears to want to clear temp_seq[] and then set all seq[] with temp_seq[] .

Answer 2

tmp_seq is declared in the function defintion as a pointer to type int . Your function is therefore always returning the size of an int * (which happens to be 4 bytes in this case).