user2520051 - 1 year ago 51

Java Question

`private static Stack<Integer> temp = new Stack<Integer>();`

public void populateSubset(int[] DATA, int fromIndex, int endIndex, int target) {

if (sumInStack == target) {

check = true ;

Counter ++ ;

print(stack, target);

}

for (int currentIndex = fromIndex; currentIndex < endIndex; currentIndex++) {

if (sumInStack + DATA[currentIndex] <= target) {

stack.push(DATA[currentIndex]);

sumInStack += DATA[currentIndex];

if (sumInStack >= MaxSumInStack){

temp = stack;

MaxSumInStack = sumInStack;

}

populateSubset(DATA, currentIndex + 1, endIndex, target);

sumInStack -= (Integer) stack.pop();

}

}

}

In subsetSum Algorithm in java, i want to find the subset with the nearest value to the target if the algorithm find no subset that has the exact sum.

In each time i update the sumInsStack, i store the stack and the sum to find the max sum. But finally the temp stack is null and nothing in it, although in each step it gets value. what should i do?

P.S: I also want to print all stacks with the max value.

Answer Source

If by

```
temp = stack;
```

you intend to make a copy of the `Stack`

, that's not what you are doing. You only make the `temp`

variable refer to the same `Stack`

as the `stack`

variable, so it you later empty `stack`

, you also empty `temp`

.

In order to make a copy, you'll have to copy the elements of the original stack to the `temp`

stack explicitly :

```
temp = new Stack<Integer>();
temp.addAll(stack);
```