【C++】【LeetCode】53. Maximum Subarray

题目

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.

思路

从头开始遍历数组，如果数组遍历到某处，之前的sum已经小于0，则没有必要加到后面的运算中，因为始终比当前数的和小。所以当sum<0时，直接舍弃。

代码

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