连续子数组中的最大和

题目描述

Find the contiguous subarray within an array (containing at least one number) which has the largest sum.

For example, given the array [-2,1,-3,4,-1,2,1,-5,4],
the contiguous subarray [4,-1,2,1] has the largest sum = 6.

代码实现1（Java）

public class MaxSubArray {
    public static void main(String[] args) {
        int[] nums = {-2,1,-3,4,-1,2,1,-5,4};
        //            -2 1 -2 4  3 5 6 -1 4
        System.out.println(new MaxSubArray().maxSubArray(nums));
    }

    public int maxSubArray(int[] nums) {
        int n = nums.length;
        int[] dp = new int[n];//dp[i] means the maximum subarray ending with array[i];
        dp[0] = nums[0];
        int max = dp[0];

        for(int i = 1; i < n; i++){
            dp[i] = nums[i] + (dp[i - 1] > 0 ? dp[i - 1] : 0);
            //System.out.println(dp[i]);
            max = Math.max(max, dp[i]);
        }

        return max;
    }
}

代码实现2（Java）

是解法1的加强版。

public class Solution {
    public int FindGreatestSumOfSubArray(int[] array) {
        if(array == null || array.length == 0) return 0;
        int a = array[0];
        int max = array[0];
        for(int i = 1;i < array.length;i++){
            a = array[i] + (a > 0 ? a : 0);
            max = Math.max(max, a);
        }
        return max;
    }
}

题目及解法均来源于leetcode