大和

package 最大数组子和;
public class FindMaxSumOfSubArray {

    /**
     * @param args
     */
    public static void main(String[] args) {
        FindMaxSumOfSubArray f = new FindMaxSumOfSubArray();
        int[] arr = { 1, -2, 3, 10, -4, 7, 2, -5 };
        System.out.println("MaxSum:" + f.findMaxSum(arr));
    }

    public Integer findMaxSum(int[] arr) {
        int curSum = 0;
        int maxSum = 0;
        int len = arr.length;

        if (arr == null || len == 0) {
            return null;
        }

        for (int i = 0; i < len; i++) {
            curSum += arr[i];
            if (curSum < 0) {
                curSum = 0;
            }
            if (curSum > maxSum) {
                maxSum = curSum;
            }
        }

        // all data are negative
        if (maxSum == 0) {
            for (int i = 0; i < len; i++) {
                if (i == 0) {
                    maxSum = arr[i];
                }
                if (arr[i] > maxSum) {
                    maxSum = arr[i];
                }
            }
        }
        return maxSum;
    }
}