最大连续子数组的积

最大连续子数组的积

不考虑溢出，注意多个0，多个负数，还有结果是1的情况

public class MaxSubMultiplication {
    public static int calculate(int[] array) {
        int lastZeroIndex = -1;
        int indexOfFirstNegative = -1;
        int indexOfLastNegative = -1;
        int mulBeforeFirst = 1;
        int mulAfterLast = 1;
        int mulOfAll = 1;
        boolean hasPositive = false;
        int max = 0;

        for (int i = 0; i < array.length; i++) {
            if (array[i] == 0) {
                if (mulOfAll > 0) {
                    if (max < mulOfAll)
                        max = mulOfAll;
                } else if (mulOfAll < 0) {
                    for (int j = lastZeroIndex + 1; j <= indexOfFirstNegative - 1; j++) {
                        mulBeforeFirst *= array[j];
                    }

                    for (int k = indexOfLastNegative + 1; k <= i - 1; k++) {
                        mulAfterLast *= array[k];
                    }

                    int cadidateOne = (mulOfAll / mulBeforeFirst) / array[indexOfFirstNegative];
                    int cadidateTwo = (mulOfAll / mulAfterLast) / array[indexOfLastNegative];
                    int result = maxOfFour(mulBeforeFirst, mulAfterLast, cadidateOne, cadidateTwo);

                    if (max < result)
                        max = result;
                }
                lastZeroIndex = i;
                indexOfFirstNegative = -1;
                indexOfLastNegative = -1;
                mulBeforeFirst = 1;
                mulAfterLast = 1;
                mulOfAll = 1;
            } else {
                if (array[i] < 0) {
                    if (indexOfFirstNegative < 0)
                        indexOfFirstNegative = i;
                    indexOfLastNegative = i;
                }
                mulOfAll *= array[i];
                if (mulOfAll > 0 || array[i] > 0)
                    hasPositive = true;
            }
        }

        if (mulOfAll > 0) {
            if (max < mulOfAll)
                max = mulOfAll;
        } else if (mulOfAll < 0) {
            for (int j = lastZeroIndex + 1; j <= indexOfFirstNegative - 1; j++) {
                mulBeforeFirst *= array[j];
            }

            for (int k = indexOfLastNegative + 1; k <= array.length - 1; k++) {
                mulAfterLast *= array[k];
            }

            int cadidateOne = (mulOfAll / mulBeforeFirst) / array[indexOfFirstNegative];
            int cadidateTwo = (mulOfAll / mulAfterLast) / array[indexOfLastNegative];
            int result = maxOfFour(mulBeforeFirst, mulAfterLast, cadidateOne, cadidateTwo);

            if (max < result)
                max = result;
        }

        return (max != 1) ? max : (hasPositive ? max : 0);
    }

    private static int maxOfFour(int a, int b, int c, int d) {
        int max = a;
        if (max < b)
            max = b;
        if (max < c)
            max = c;
        if (max < d)
            max = d;
        return max;
    }

    public static void main(String[] args) {
        int[] array = { -1, 0, -2, 1, 0, -6, 0, -7 };
        System.out.println(MaxSubMultiplication.calculate(array));
    }

}