Partition algorithm

Question

I am receiving java.lang.ArrayIndexOutOfBoundsException: 10 after running this code.

How can I limit my code to only 9 index values or find an alternative way to correct this?

int p = theArray[first]; // use the first item of the array as the pivot p      
int lastS1 = first;      // set S1 and S2 to empty

// ToDo: Determine the regions S1 and S2
// Refer to the partition algorithm on page 495 of the textbook.

for (int i = lastS1; i < last; i++)
    if (theArray[i] < p) {
        for (int j = i ; j > 0 && j >= p ; j--)
            swap(theArray, j, j - 1);
    }

lastS1++;

return lastS1;

Please indent your code and give a workable example, this one just not have the definition of the function — azro, Mar 08 '18 at 21:04
Seems your code is incomplete: what is the value of 'first'? — рüффп, Mar 08 '18 at 21:09

clinomaniac · Answer 1 · 2018-03-09T00:24:49.897

0

You can use for (int i = lastS1; i < last - 1; i++).

You need to use last - 1 because in Java, arrays are 0 indexed. Means they start from 0 and go to length - 1.

edited Mar 09 '18 at 00:24

answered Mar 08 '18 at 21:06

clinomaniac

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While this might prevent the exception, would you please add a slightly more detailed explanation why you think that this implements the intended behavior of the algorithm? – Andrey Tyukin Mar 09 '18 at 00:23

Partition algorithm

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