Recursive Rollback

Question

I had a problem with my backtracking function, these are loops with certain data, I can’t write all the program code here, but I can put my own function here.

bool shareMoney(int quantity, int *values, int index, int moneyA, int half, bool *ifChosen)
{

    if(moneyA == half)
        return true;
    else if(index >= quantity)
        return false;

    moneyA += values[index];

    if(shareMoney(quantity, values,index+1, moneyA, half, ifChosen))
    {
        ifChosen[index] = true;
        return true;
    };

    moneyA -= values[index];

    if(shareMoney(quantity, values,index+1, moneyA, half, ifChosen))
    {
        ifChosen[index] = false;
        return true;
    };

    return false;
}

Now here is the explanation:

quantity - the number of elements in the array of values
values ​​- an array of numbers
index - a variable for managing recursion
moneyA - a variable that stores the sum of the element from the array values
half the number that money should reach after completing the recursion
ifChosen - an array of logical elements that refers to the values array

, , , , 0, , moneyA, , , , ifChosen .

, , , moneyA ifChosen, , , ifChosen moneyA. .

:

6 - number of elements
50, 20, 19, 15, 2, 2 - elements stored in values array
total sum is - 108
half of elements - 54

:

50, 2, 2 - marked as true in ifChosen
20, 19, 15 - marked as false in ifChosen 

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:

89 86 83 67 53 45 5 1    

44 43 34 33 33 24 23 23 23 22 21 21 19 12 11 9 8 7 5 3 2 2 2 1 1 1 1 1     

real    0m28.007s    

user    0m27.926s    

sys 0m0.028s

, , , : 43 :

12 2 2 1 3 4 5 6 7 89 33 12 45 23 44 23 11 44 1 3 5 7 88 33 8 19 43 22 86 5 34 23 21 67 83 24 21 53 9 11 34 1 1

@Karl Bielefeldt , , , . , , . - , , ?

bool shareMoney(int quantity, int *values, int index, int moneyA, int half, bool *ifChosen){

if(index>=quantity && moneyA == half){ return true;}
else if(index>=quantity) return false;

moneyA+=values[index];
ifChosen[index]=true;

if(moneyA<=half){       
    shareMoney(quantity,values,index+1,moneyA, half,ifChosen);
    if(moneyA==half) return true;

    return true;
}else{
    shareMoney(quantity,values,index+1,moneyA, half,ifChosen);      
    moneyA-=values[index];
    ifChosen[index]=false;

    return true;
}


return false;}

Answer 1

(, , ). Simplex . , , , , , , , .

EDIT: :

int* shareMoney( int pool_size, int *pool, int *solution, int cumsum, int goal)
{
    if (cumsum == goal) return solution;
#if PRUNE_ABOVE
    if (cumsum > goal) return 0;
#endif
    if (!pool_size) return 0;

#if PRUNE_BELOW
    int max = cumsum;
    for( int n = pool_size; n--; max += pool[n] );
    if (max < goal) return 0;
#endif

    int* subproblem = shareMoney(pool_size-1, pool+1, solution, cumsum, goal);
    if (subproblem) return subproblem;

    *solution = *pool;
    return shareMoney(pool_size-1, pool+1, solution+1, cumsum+*pool, goal);
}

solution , , .

- . .

max :

int* shareMoney( int pool_size, int *pool, int *solution, int cumsum, int poolsum, int goal)
{
    if (cumsum == goal) return solution;
#if PRUNE_ABOVE
    if (cumsum > goal) return 0;
#endif
    if (!pool_size) return 0;

#if PRUNE_BELOW
    if (cumsum + poolsum < goal) return 0;
#endif

    int* subproblem = shareMoney(pool_size-1, pool+1, solution, cumsum, poolsum - *pool, goal);
    if (subproblem) return subproblem;

    *solution = *pool;
    return shareMoney(pool_size-1, pool+1, solution+1, cumsum+*pool, poolsum - *pool, goal);
}

( ):

int* shareMoney( int pool_size, int *pool_denom, int *pool_cardinality, int *solution, int cumsum, int poolsum, int goal)
{
    if (cumsum == goal) return solution;
#if PRUNE_ABOVE
    if (cumsum > goal) return 0;
#endif
    if (!pool_size) return 0;

#if PRUNE_BELOW
    if (cumsum + poolsum < goal) return 0;
#endif

    poolsum -= *pool_cardinality * *pool_denom;
    for (*solution = *pool_cardinality; *solution >= 0; --*solution) {
        int* subproblem = shareMoney(pool_size-1, pool_denom+1, pool_cardinality+1, solution+1, cumsum + *solution * *pool_denom, poolsum, goal);
        if (subproblem) return subproblem;
    }

    return 0;
}

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Answer 2

43 9 . , 9 , , . , , , , . , , ( ).

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