How to swap elements in ArrayList<ArrayList<Integer>>?

user_14933653 0
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I'm trying to swap elements in ArrayList<ArrayList<Integer>>. I wanted to know either an inbuilt function if present any or brute-force approach to solve : swap(mat.get(i).get(j),mat.get(j).get(i+1)) swapping these 2 elements in a ArrayList<ArrayList<Integer>>.

swap arraylist java
1 Answers

I don't believe there is a built-in function to swap these two elements.

A brute force solution would have to store one value in another variable and then swap them in O(1) time.

Something like:

void swap(int i, int j){
    int val = bigList.get(i).set(j, bigList.get(i+1).get(j));
    bigList.get(i+1).set(j, val);
}

--Where 'bigList' is the parent ArrayList containing ArrayLists.

Hope this helps!

user_198824390
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