元宝 LeetCode 327. Count of Range Sum Java Implement
Core idea: prefix sums merge sort. The problem becomes: given prefix sum array
“pre”, count pairs
“(i, j)” with
“i < j” and
“lower ≤ pre[j] - pre[i] ≤ upper”. During merge, both halves are sorted, so two moving pointers count every valid cros…
2026/10/13 7:03:19 阅读全文 →