leetcode--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.

题意：在数组中，查找一个连续的子数组，使它的元素有最大和，求最大和

分类：数组，动态规划

解法1：很经典的动态规划题目。关键是找到规划关系。

设flag[i]，我们知道，每个子数组，都必然以一个元素结尾，所有flag[i]就代表，以元素nums[i]为结尾的子数组的最大和

那么来考虑flag[i+1]，对于它只有两种选择，一个是nums[i+1]，一个是nums[i+1]+flag[i]

所以关系就是flag[i+1]=Max(nums[i+1]，nums[i+1]+flag[i]);

public class Solution {    public int maxSubArray(int[] nums) {        int res[] = new int[nums.length];int max = nums[0];res[0] = nums[0];for(int i=1;i<nums.length;i++){if(res[i-1]+nums[i]<nums[i]){res[i] = nums[i];}else{res[i] = res[i-1]+nums[i];}if(max<res[i]){max = res[i];}}return max;    }}