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| class SegTreeMax { public: struct node { int l, r; int v; }; int N = 1e5+10; vector<node> tr; SegTreeMax(int x) : N(x){ tr.resize(4*N); build(1, 1, N); }; void build(int u, int l, int r) { tr[u] = {l, r}; if(l == r) return ; int mid = (l + r) >> 1; build(u << 1, l, mid); build(u << 1 | 1, mid+1, r); } void pushup(int u) { tr[u].v = max(tr[u<<1].v, tr[u<<1|1].v); } void modify(int u, int x, int w) { if(tr[u].l == x && tr[u].r == x) tr[u].v = w; else { int mid = (tr[u].l + tr[u].r) >> 1; if(x <= mid) modify(u<<1, x, w); else modify(u<<1|1, x, w); pushup(u); } } int query(int u, int l, int r){ if(tr[u].l >= l && tr[u].r <= r) return tr[u].v; int mid = (tr[u].l + tr[u].r) >> 1, ans = 0; if(l <= mid) ans = query(u<<1, l, r); if(r > mid) ans = max(ans, query(u<<1|1, l, r)); return ans; } };
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