leetcode

Solution to some Leetcode problems written in C++

git clone git://git.dimitrijedobrota.com/leetcode.git

segment_tree.cpp (619B)

0 class SegmentTree { 1 const int n; 2 vector<int> t = vector<int>(2 * n); 3 4 public: 5 SegmentTree(const vector<int> nums): n(size(nums)) { 6 for (int i = 0; i < n; i++) t[n + i] = nums[i]; 7 for (int i = n - 1; i > 0; i--) t[i] = t[i * 2] + t[i * 2 + 1]; 8 } 9 10 int sum(int l, int r) const { 11 int res = 0; 12 13 for (l += n, r += n; l < r; l /= 2, r /= 2) { 14 if (l & 1) res += t[l++]; 15 if (r & 1) res += t[--r]; 16 } 17 18 return res; 19 } 20 21 void update(int p, int val) { 22 for (t[p += n] = val; p > 1; p /= 2) t[p / 2] = t[p] + t[p ^ 1]; 23 } 24 };