[Leetcode-53]Maximum Subarray 最大子数组和

0. 题目概要

Leetcode 53. Maximum Subarray
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.

翻译：
一个整数数组， 一个非空的子数组(连续一段数)， 使得它的和最大。

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1. 分析

线性枚举方法：

2. AC代码 C++

• 线性枚举方法：
  

class Solution {
public:
    int maxSubArray(vector<int>& nums) {
        size_t n = nums.size();
        int sum = nums[0];
        int answer = nums[0];
        int minSum = min(0, sum);
        for(int i=1; i< n; i++){
            sum += nums[i];
            answer = max(answer, sum - minSum);
            minSum = min(minSum, sum);
        }

        return answer;
    }
};

3. AC代码 Java

• 线性枚举方法：
  

public class Solution {
    public int maxSubArray(int[] nums) {
        int n = nums.length;
        int sum = nums[0];
        int answer = nums[0];
        int minSum = Math.min(0, sum);
        for(int i=1; ireturn answer;
    }
}