给定一个整数数组 nums ，找到一个具有最大和的连续子数组（子数组最少包含一个元素），返回其最大和。
示例:
输入: [-2,1,-3,4,-1,2,1,-5,4],
输出: 6
解释: 连续子数组 [4,-1,2,1] 的和最大，为 6。
class Solution {
public:
int maxSubArray(vector<int>& nums) {
int low = 0;
int high = nums.size() - 1;
return divid(nums, low, high);
}
int divid(std::vector<int>& a, int low,int high) {
int s1 = 0, s2 = 0, s3 = 0;
if (low == high) {
return a[low];
}
else{
int mid = (low + high) / 2;
s1 = divid(a, low, mid);
s2 = divid(a, mid + 1, high);
s3 = crossingSubArray(a, low, mid, high);
int s = (s1 > s2) ? s1 : s2;
return s3 > s ? s3 : s;
}
}
int crossingSubArray(std::vector<int>& a, int low, int mid, int high) {
int Sleft = a[mid];
int Sright = a[mid + 1];
int sumLeft = 0, sumRight = 0;
for (int i = mid; i >= low; i--) {
sumLeft += a[i];
Sleft = (Sleft > sumLeft) ? Sleft : sumLeft;
}
for (int j = mid+1; j <= high; j++) {
sumRight += a[j];
Sright = (Sright > sumRight) ? Sright : sumRight;
}
return Sleft + Sright;
}
};
