import sequtils,strutils,strscans,algorithm,math,future,sets,queues,tables,macros macro unpack*(rhs: seq,cnt: static[int]): auto = let t = genSym(); result = quote do:(let `t` = `rhs`;()) for i in 0..= size : break let child = if R < size and h.compareNode(R,L) <= 0 : R else: L if h.compareNode(i,child) <= 0: break swap(h.nodes[i],h.nodes[child]) i = child proc pushimpl[T](h:var BinaryHeap[T],node:T):void = h.nodes.add(node) #末尾に追加 var i = h.nodes.len() - 1 while i > 0: # 末尾から木を整形 let parent = (i - 1) div 2 if h.compare(h.nodes[parent],node) <= 0: break h.nodes[i] = h.nodes[parent] i = parent h.nodes[i] = node proc popimpl[T](h:var BinaryHeap[T]):T = result = h.nodes[0] # rootと末尾を入れ替えて木を整形 h.nodes[0] = h.nodes[^1] h.nodes.setLen(h.nodes.len() - 1) h.shiftdown() ######################## Binary Heap ############################# # 0以下で死亡 / V - Lxy => Oasis(v *= 2,once) # N <= 200, V <= 500, Lxy <= 9 # x:N * y:N * use:2 => V # 最短でゴール or 最短でオアシス +最短でゴールのみ let (N,V,oax,oay) = get().split().map(parseInt).unpack(4) L = newSeqWith(N,get().strip().split().map(parseInt)).transpose() (ox,oy) = (oax-1,oay-1) ## とりあえずダイクストラ ########################################## proc dijkestra(sx,sy:int, L:seq[seq[int]],diffSeq:seq[tuple[x,y:int]]):auto = type field = tuple[x,y,v:int] let (W,H) = (L.len,L[0].len) const INF = int.high div 4 var cost = newSeqWith(W,newSeqWith(H,INF)) var opens = newBinaryHeap[field](proc(a,b:field): int = a.v - b.v) opens.push((sx,sy,0)) while opens.size() > 0: let (x,y,v) = opens.pop() if cost[x][y] != INF : continue cost[x][y] = v for d in diffSeq: let (nx,ny) = (d.x + x,d.y + y) if nx < 0 or ny < 0 or nx >= W or ny >= H : continue var n_v = v + L[nx][ny] if cost[nx][ny] == INF : opens.push((nx,ny,n_v)) return cost let b2cost = dijkestra(0,0,L,dxdy4) b2e = b2cost[N-1][N-1] if ox == -1 and oy == -1 : if V - b2e > 0: echo "YES" else: echo "NO" else: let b2o = b2cost[ox][oy] o2cost = dijkestra(ox,oy,L,dxdy4) o2e = o2cost[N-1][N-1] if V - b2e > 0 or 2 * (V - b2o) - o2e > 0 : echo "YES" else: echo "NO" ############## 二段階にわける (27ms:結局全探索しないといけないものには勝てない) ##################### #[ proc twoFactorDijkestra(sx,sy,sv:int,checkOasis:bool = true):void = type field = tuple[x,y,v:int] var closed = newSeqWith(N,newSeqWith(N,false)) var opens = newBinaryHeap[field]( proc(a,b:field): int = -a.v + b.v) opens.push((sx,sy,sv)) while opens.size() > 0: let (x,y,v) = opens.pop() if closed[x][y] : continue closed[x][y] = true if checkOasis and x == ox and y == oy: twoFactorDijkestra(x,y,v * 2,false) continue for d in dxdy4: let (nx,ny) = (d.x + x,d.y + y) if nx < 0 or ny < 0 or nx >= N or ny >= N : continue var n_v = v - L[nx][ny] if n_v <= 0 : continue if not closed[nx][ny]: opens.push((nx,ny,n_v)) if nx == N-1 and ny == N-1: echo "YES" quit() twoFactorDijkestra(0,0,V) echo "NO" ]# #[ ############## use dijekstra all in one (33ms) ############### type field = tuple[x,y,used,v:int] var closed = newSeqWith(N,newSeqWith(N,[false,false])) var opens = newBinaryHeap[field]( proc(a,b:field): int = #-a.v + b.v if a.used != b.used : - a.used + b.used # オアシスを使ったほうが強い else : -a.v + b.v #elif a.v != b.v : - a.v + b.v # 基本は体力をコスト関数とする #else: - (a.x + a.y) + (b.x + b.y) ) opens.push((0,0,false.int,V)) proc dijkstra():void = while opens.size() > 0: let (x,y,used,v) = opens.pop() if closed[x][y][used] : continue closed[x][y][used] = true #echo((x:x,y:y,u:used,v:v)) for d in dxdy4: let (nx,ny) = (d.x + x,d.y + y) if nx < 0 or ny < 0 or nx >= N or ny >= N : continue var n_used = used n_v = v - L[nx][ny] if n_v <= 0 : continue if nx == ox and ny == oy and (not used.bool): n_used = true.int n_v *= 2 if not closed[nx][ny][n_used]: opens.push((nx,ny,n_used,n_v)) if nx == N-1 and ny == N-1: echo "YES" quit() dijkstra() echo "NO" ]# #[ ########### DP ( 533ms ) ########################### var dp = newSeqWith(N,newSeqWith(N,[OPEN,OPEN])) proc dp_seek(x,y,used:int): void = if x == N-1 and y == N-1: echo "YES" quit() for d in dxdy4: let (nx,ny) = (d.x + x,d.y + y) if nx < 0 or ny < 0 or nx >= N or ny >= N : continue var n_used = used v = dp[x][y][used] - L[nx][ny] if isOasis(nx,ny) and (not used.bool): n_used = true.int v *= 2 if dp[nx][ny][n_used] < v and v > 0: dp[nx][ny][n_used] = v dp_seek(nx,ny,n_used) dp_seek(0,0,false.int) echo "NO" ]#