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Minimum Loss

  • gschoen
     + 0 comments

    When you need to sort the data but keep track of the original index positions, use a pair-index structure. In the code below, the 'quickSort()` routine sorts by price in non-increasing order and for elements that have have the same price, it sorts by index in increasing order.

    typedef struct {
    long long price;
    int index;
} Pair;

void quickSort(void **a, int lo, int hi);

int minimumLoss(long long* price, int n) {
    long long minLoss = 1e16;
    Pair *pair[n], p[n];
    for (int i = 0; i < n; ++i) {
        pair[i] = &p[i];
        p[i].price = price[i];
        p[i].index = i;
    }
    quickSort((void**) pair, 0, n-1);
    for (int i = 0; i < n-1; ++i) {
        if (pair[i]->index > pair[i+1]->index) continue;
        long long loss = pair[i]->price - pair[i+1]->price;
        if (loss < minLoss) minLoss = loss;
    }
    return minLoss;
}