CODEWITHSUNDEEP
c++
user1113314
user1113314

Reputation: 839

Strange program behavior

So I wanted to write code which solves this problem: "Collecting Beepers" And I did:

int rec(int current, int beers)
{
    if(beers == (1 << (numOfBeers + 1)) - 1) return cost(beerX[0], beerY[0], beerX[current], beerY[current]);
    int optimal = 100000;
    for(int i = 1; i <= numOfBeers; ++i)
    {
        if(((1 << i) & beers) == 0)
        {
            int newBeersSet = (1 << i) | beers;
            int c = cost(beerX[current], beerY[current], beerX[i], beerY[i]);
            int current = c + rec(i, newBeersSet);
            optimal = min(optimal, current);
        }
    }
    return optimal;
}

The strange thing is, that when I replace the part

int c = cost(beerX[current], beerY[current], beerX[i], beerY[i]);
int current = c + rec(i, newBeersSet);

with

int current = cost(beerX[current], beerY[current], beerX[i], beerY[i]) + rec(i, newBeersSet);

the logic is absolutely the same and yet my program crashes on the same (the one given in the problem desciption) input and the online judge gives wrong answer as a result from the program execution while with the original code it gives Accepted. Any ideas what could possibly be wrong?

Upvotes: 2

Views: 84

Answers (2)

Ole Dittmann
Ole Dittmann

Reputation: 1774

That is propably because your variable "current" is overriden. Try:

int current2 = cost(beerX[current], beerY[current], beerX[i], beerY[i]) + rec(i, newBeersSet);
optimal = min(optimal, current2);

Upvotes: 2

M.M
M.M

Reputation: 141618

In this line you are using an uninitialized variable:

int current = cost(beerX[current],  // ...

This declares a new variable current and then, before the variable has had a value assigned, uses it as index to beerX.

You probably meant:

int new_current = cost(beerX[current],  // ...

which uses the existing current variable which was declared in the parameter list for the rec function.

Upvotes: 2

Related Questions