题目：

题解：

int countRangeSumRecursive(long long* sum, int lower, int upper, int left, int right) {if (left == right) {return 0;} else {int mid = (left + right) / 2;int n1 = countRangeSumRecursive(sum, lower, upper, left, mid);int n2 = countRangeSumRecursive(sum, lower, upper, mid + 1, right);int ret = n1 + n2;// 首先统计下标对的数量int i = left;int l = mid + 1;int r = mid + 1;while (i <= mid) {while (l <= right && sum[l] - sum[i] < lower) l++;while (r <= right && sum[r] - sum[i] <= upper) r++;ret += (r - l);i++;}// 随后合并两个排序数组long sorted[right - left + 1];memset(sorted, 0, sizeof(sorted));int p1 = left, p2 = mid + 1;int p = 0;while (p1 <= mid || p2 <= right) {if (p1 > mid) {sorted[p++] = sum[p2++];} else if (p2 > right) {sorted[p++] = sum[p1++];} else {if (sum[p1] < sum[p2]) {sorted[p++] = sum[p1++];} else {sorted[p++] = sum[p2++];}}}for (int i = 0; i < right - left + 1; i++) {sum[left + i] = sorted[i];}return ret;}
}int countRangeSum(int* nums, int numsSize, int lower, int upper) {long long s = 0;long long sum[numsSize + 1];sum[0] = 0;for (int i = 1; i <= numsSize; i++) {sum[i] = sum[i - 1] + nums[i - 1];}return countRangeSumRecursive(sum, lower, upper, 0, numsSize);
}