线段树

线段树

struct Node{
    int l, r, sum, lazy;
}tr[N * 4];

int a[N];

void pushup(int u) {
    tr[u].sum = tr[u << 1].sum + tr[u << 1 | 1].sum;
}

void pushdown(int u) {
    if (tr[u].lazy) {
        tr[u << 1].sum += tr[u].lazy * (tr[u << 1].r - tr[u << 1].l + 1);
        tr[u << 1 | 1].sum += tr[u].lazy * (tr[u << 1 | 1].r - tr[u << 1 | 1].l + 1);
        tr[u << 1].lazy += tr[u].lazy;
        tr[u << 1 | 1].lazy += tr[u].lazy;
        tr[u].lazy = 0;
    }
}

void build(int u, int l,int r) {
    tr[u] = {l, r, a[l], 0};
    if (l == r)return;
    int mid = l + r >> 1;
    pushdown(u);
    build(u << 1, l, mid);
    build(u << 1 | 1, mid + 1, r);
    pushup(u);
}
//区间修改
void modify(int u,int l,int r,int k) {
    if (tr[u].l >= l && tr[u].r <= r) {
        tr[u].sum += (tr[u].r - tr[u].l + 1) * k;
        tr[u].lazy += k;
        return;
    }
    pushdown(u);
    int mid = tr[u].l + tr[u].r >> 1;
    if (l <= mid)modify(u << 1, l, r, k);
    if (r > mid) modify(u << 1 | 1, l, r, k);
    pushup(u);
}
//单点修改
void modify(int u,int x,int k) {
    if (tr[u].l == tr[u].r) {
        tr[u].sum += k;
        return;
    }
    int mid = tr[u].l + tr[u].r >> 1;
    if (x <= mid)modify(u << 1, x, k);
    else modify(u << 1 | 1, x, k);
}
//区间查询
int query(int u,int l,int r) {
    if (tr[u].l >= l && tr[u].r <= r) return tr[u].sum;
    pushdown(u);
    int sum = 0;
    int mid = tr[u].l + tr[u].r >> 1;
    if (l <= mid)sum += query(u << 1, l, r);
    if (r > mid) sum += query(u << 1 | 1, l, r);
    return sum;
}
//单点点查询
int query(int u,int x) {
    if (tr[u].l == tr[u].r)return tr[u].sum;
    pushdown(u);
    int mid = tr[u].l + tr[u].r >> 1;
    if (x <= mid)return query(u << 1, x);
    else return query(u << 1 | 1, x);
}