数据结构——线段树 学习笔记

class seg_t {

private:

struct emm {
    int l, r;
    struct v;
};

vector<emm> a;

void push_up(int k) { }
void action(int k, int v) { }
void push_down(int k) { }

void build(vector<any> q, int k, int l, int r) {
    a[k].l = l, a[k].r = r;
    if (l == r) { return; }
    int mid = l + (r - l >> 1);
    build(q, k * 2, l, mid);
    build(q, k * 2 + 1, mid + 1, r);
    push_up(k);
}

void modify(int k, int p, int q, int v) {
    auto &l = a[k].l, &r = a[k].r;
    if (l >= p && r <= q) return void(action(k, v));
    int mid = l + (r - l >> 1);
    if (mid >= p)     modify(k * 2, p, q, v);
    if (mid + 1 <= q) modify(k * 2 + 1, p, q, v);
    push_up(k);
}

int query(int k, int p, int q) {
    auto &l = a[k].l, &r = a[k].r;
    int mid = l + (r - l >> 1);
    int res;
    if (mid >= p)     res += query(k * 2, p, q);
    if (mid + 1 <= q) res += query(k * 2 + 1, p, q);
    return res;
}

public:

};

然后参考：https://www.cnblogs.com/RainPPR/p/18066950/scanning

以及：https://www.cnblogs.com/RainPPR/p/17974548/segment-tree-2

没了。是不是很水？