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#1
October 1st, 2012, 10:17 AM
 romavolman
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Homework - How to do write this method with more efficiency ?

The program below accept two array with hole pozitive nums, with same size N, and fill empty array "c" with nums of "a" that do not exist in "b" and return the biggest num of "a" that do not exist in "b".
qustion: how to do write this method with more efficiency ?

[PHP]
public int f(int[]a, int[]b, int[] c)
{
int N = a.length;
int j, max = 0, g = 0, t = 0;

for(int i=0; i < N; i++)
{
for(j=0; j<N; j++)
if(b[j] == a[i]) // if find the num in "b" go to the next num in "a"
break;

if(j == N)
{
c[t] =a[i] // fill empty array "c" with nums of "a" that do not exist in "b"
if(g ==0 || c[t] > max)
{
max = c[t]; // remmber the max num in "max"
g = 1;

}
t++;

}

}
return max; // max of "a" that you do not have in "b"

[\PHP]

#2
October 2nd, 2012, 03:55 PM
 doa24uk
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If the are guaranteed to be the same size then

Store the size of a or b in an int.

Hold a seperate counter variable that increments one at a time.
Hold a seperate variable for the current max number.

Loop through the specified number of times (which == the size of array a).
If elementA(count) != elementB(count)
{
// add to array list c
// set the new max number to be this number
}
// Now we're at the end of the loop.

// Print out the max number

#3
October 3rd, 2012, 05:09 AM
 ishnid
kill 9, \$\$;

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Quote:
 Originally Posted by doa24uk If the are guaranteed to be the same size then Store the size of a or b in an int. Hold a seperate counter variable that increments one at a time. Hold a seperate variable for the current max number. Loop through the specified number of times (which == the size of array a). If elementA(count) != elementB(count) { // add to array list c // set the new max number to be this number } // Now we're at the end of the loop. // Print out the max number

That only checks if 'a' and 'b' contain the same elements in the same position in the array, which isn't the original problem.

Hint to OP: this is much more efficient of 'a' and 'b' are sorted.

#4
October 6th, 2012, 07:31 AM
 doa24uk
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Quote:
 Originally Posted by ishnid That only checks if 'a' and 'b' contain the same elements in the same position in the array, which isn't the original problem. Hint to OP: this is much more efficient of 'a' and 'b' are sorted.

Doh! Of course, you are correct.

Collections.sort()

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