53. Maximum Subarray
Easy
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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.
定义两个变量res和curSum，其中res保存最终要返回的结果，即最大的子数组之和，curSum初始值为0，每遍历一个数字num，比较curSum + num和num中的较大值存入curSum，然后再把res和curSum中的较大值存入res，以此类推直到遍历完整个数组，可得到最大子数组的值存在res中，代码如下：
class Solution {
public:
int maxSubArray(vector<int>& nums) {
int res = INT_MIN, curSum = 0;
for (int num : nums) {
curSum = max(curSum + num, num);
res = max(res, curSum);
}
return res;
}
};
运行结果：