求最大子数组的和

一、暴力求解法

//对每一个可能的组合求和，然后比较最大的和.  

 public static int FindGreatestSumOfSubArray(int[] array) {
        ArrayList result = new ArrayList();
        for (int i = 0; i < array.length; i++) {
            for (int j = array.length - 1; j >= i; j--) {
                result.add(getsum(array, i, j));
            }
        }
        Collections.sort(result);
        return result.get(result.size()-1);
    }


    public static int getsum(int[] s, int i, int j) {
        int sum = 0;
        for (int k = i; k <= j; k++) {
            sum += s[k];
        }
        return sum;
    }

二、扫描法

    

public int maxSum(int[] array){
        int sum = Integer.MIN_VALUE;
        int current = 0;
        for (int i = 0; i < array.length; i++) {
            if(array[i]<0){
                current = array[i];
            }else {
                current+=array[i];
            }
            if(sum

这个问题的常见场景计算股票最大的收益