LeetCode 53. Maximum Subarray

题目描述

Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.

Example:
Input: [-2,1,-3,4,-1,2,1,-5,4],
Output: 6
Explanation: [4,-1,2,1] has the largest sum = 6.

Follow up:
If you have figured out the O(n) solution, try coding another solution using the divide and conquer approach, which is more subtle.

题目思路

• <剑指Offer>面试题42: 连续子数组的最大和

代码 C++

• 思路一、举例分析数组的规律

class Solution {
public:
    int maxSubArray(vector& nums) {
        int max = nums[0];
        int temp = 0;
        
        for(int i=0; i < nums.size(); i++){
            if(temp + nums[i] > nums[i]){
                temp += nums[i];
            }
            else{
                temp = nums[i];
            }
            
            if(max < temp){
                max = temp;
            }
        }
        
        return max;
    }
};

• 思路二、动态规划法

class Solution {
public:
    int maxSubArray(vector& nums) {
        int max = nums[0];
        int temp = 0;
        
        for(int i=0; i < nums.size(); i++){
            temp = temp+nums[i]>nums[i] ? temp+nums[i] : nums[i];
            max = max > temp? max : temp;
        }  
        return max;
    }
};

总结展望