這題使用把兩個賦值
for (int i = st; i <= mid; i++)
{
int m = mid;
int n = mid;
while (m <= ed && sums[m] - sums[i] < lower) m++;
while (n <= ed && sums[n] - sums[i] <= upper) n++;
count += n-m;
}
像下面這樣 換到for循壞外就不會超時了
int m = mid;
int n = mid;
for (int i = st; i < mid; i++)
{
while (m < ed && sums[m] - sums[i] < lower) m++;
while (n < ed && sums[n] - sums[i] <= upper) n++;
count += n-m;
}