import strutils, sequtils, algorithm, future, tables, sets type PrirorityQueue*[T] = ref object of RootObj elms: seq[T] idxs: TableRef[T, int] cmp: (T, T) -> int proc newPriorityQueue*[T](cmp: (T, T) -> int): PrirorityQueue[T] = new(result) result.elms = newSeq[T]() result.idxs = newTable[T, int]() result.cmp = cmp template parent(cur: int): int = if cur == 0: -1 else: (cur - 1) div 2 template childl(cur: int): int = cur * 2 + 1 template childr(cur: int): int = cur * 2 + 2 proc innerDel[T](self: var PrirorityQueue[T], cur: int) = self.idxs.del(self.elms[cur]) self.elms.del(cur) proc innerSwap[T](self: var PrirorityQueue[T], s, t: int) = let (sval, tval) = (self.elms[s], self.elms[t]) swap(self.elms[s], self.elms[t]) swap(self.idxs[sval], self.idxs[tval]) proc valid[T](self: PrirorityQueue[T], upper, lower: int): bool = let val = self.cmp(self.elms[upper], self.elms[lower]) assert(val != 0) result = val < 0 proc valid[T](self: PrirorityQueue[T], cur: int = 0): bool = var (chl, chr) = (childl(cur), childr(cur)) result = true if chl < self.len: result = result and self.valid(cur, chl) result = result and self.valid(chl) if chr < self.len: result = result and self.valid(cur, chr) result = result and self.valid(chr) proc upHeap[T](self: var PrirorityQueue[T], cur: var int) = var par = parent(cur) while par >= 0 and not self.valid(par, cur): self.innerSwap(cur, par) (cur, par) = (par, parent(par)) proc downHeap[T](self: var PrirorityQueue[T], cur: var int) = var (chl, chr) = (childl(cur), childr(cur)) while chl < self.elms.len: var ch = if chr >= self.elms.len or self.valid(chl, chr): chl else: chr if self.valid(cur, ch): break self.innerSwap(cur, ch) (cur, chl, chr) = (ch, childl(ch), childr(ch)) proc len*[T](self: PrirorityQueue[T]): int = assert(self.elms.len == self.idxs.len) self.elms.len proc push*[T](self: var PrirorityQueue[T], data: T): bool {.discardable.} = if self.idxs.contains(data): return false var n = self.elms.len cur = n self.elms.setLen(n + 1) self.elms[cur] = data self.idxs[data] = cur self.upHeap(cur) return true proc peek*[T](self: var PrirorityQueue[T]): T = self.elms[0] proc pop*[T](self: var PrirorityQueue[T]): T {.discardable.} = assert(self.elms.len > 0) var n = self.elms.len cur = 0 result = self.elms[0] self.innerSwap(0, n-1) self.innerDel(n-1) self.downHeap(cur) proc del*[T](self: var PrirorityQueue[T], data: T): bool {.discardable.} = if not self.idxs.contains(data): return false let n = self.elms.len var idx = self.idxs[data] if idx == n - 1: self.innerDel(n-1) else: self.innerSwap(idx, n-1) self.innerDel(n-1) self.downHeap(idx) self.upHeap(idx) return true # ============================================================================== when isMainModule: var n = stdin.readLine.parseInt a = stdin.readLine.split.map(parseInt) b = newSeq[int](n) lastIdx = newTable[int, int]() pQ = newPriorityQueue[int]((x: int, y: int) => y - x) for i in 0..