O(N) 求数组中最大子串和

int MaxSubSum3(int *arr, int len) {
	int i;
	long long MaxSum = 0;
	long long CurSum = 0;
	for(int i = 0; i < len; i ++) {
		CurSum += arr[i];
		if(CurSum > MaxSum)
			MaxSum = CurSum;
		if(CurSum < 0)
			CurSum = 0;
	}
	return MaxSum;
}