cp-library
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cp_library/alg/graph/csr/snippets/shortest_path_edge_ids_fn.py
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- Last update: 2025-08-24 20:27:05+09:00
Depends on
- cp_library/alg/dp/chmin_fn.py
- cp_library/alg/graph/csr/graph_base_cls.py
- cp_library/alg/graph/csr/snippets/recover_path_edge_ids_fn.py
- cp_library/alg/graph/dfs_options_cls.py
- cp_library/bit/masks/i32_max_cnst.py
- cp_library/bit/masks/u32_max_cnst.py
- cp_library/ds/array/i32f_fn.py
- cp_library/ds/array/u32f_fn.py
- cp_library/ds/array/u8f_fn.py
- cp_library/ds/list/elist_fn.py
- cp_library/ds/list/list_find_fn.py
- cp_library/ds/packet_list_cls.py
- cp_library/ds/que/que_cls.py
- cp_library/ds/view/view_cls.py
- cp_library/io/io_base_cls.py
- cp_library/io/parsable_cls.py
Verified with
Code
import cp_library.__header__
from math import inf
import cp_library.alg.__header__
import cp_library.alg.graph.__header__
import cp_library.alg.graph.csr.__header__
import cp_library.alg.graph.csr.snippets.__header__
from cp_library.alg.graph.csr.snippets.recover_path_edge_ids_fn import recover_path_edge_ids
def shortest_path_edge_ids(G: 'GraphBase', s: int, t: int):
if G.distance(s, t) >= inf: return None
P = recover_path_edge_ids(G, s, t); P.reverse()
return P
from cp_library.alg.graph.csr.graph_base_cls import GraphBase
GraphBase.shortest_path_edge_ids = shortest_path_edge_ids'''
╺━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╸
https://kobejean.github.io/cp-library
'''
from math import inf
def recover_path_edge_ids(G: 'GraphBase', s: int, t: int):
P = u32f(0)
while s != t: P.append(G.Ea[a := G.back[t]]), (t := G.Ua[a])
return P
from typing import Callable, Sequence, Union, overload
from types import GenericAlias
class Parsable:
@classmethod
def compile(cls):
def parser(io: 'IOBase'): return cls(next(io))
return parser
@classmethod
def __class_getitem__(cls, item): return GenericAlias(cls, item)
def chmin(dp, i, v):
if ch:=dp[i]>v:dp[i]=v
return ch
from enum import auto, IntFlag, IntEnum
class DFSFlags(IntFlag):
ENTER = auto()
DOWN = auto()
BACK = auto()
CROSS = auto()
LEAVE = auto()
UP = auto()
MAXDEPTH = auto()
RETURN_PARENTS = auto()
RETURN_DEPTHS = auto()
BACKTRACK = auto()
CONNECT_ROOTS = auto()
# Common combinations
ALL_EDGES = DOWN | BACK | CROSS
EULER_TOUR = DOWN | UP
INTERVAL = ENTER | LEAVE
TOPDOWN = DOWN | CONNECT_ROOTS
BOTTOMUP = UP | CONNECT_ROOTS
RETURN_ALL = RETURN_PARENTS | RETURN_DEPTHS
class DFSEvent(IntEnum):
ENTER = DFSFlags.ENTER
DOWN = DFSFlags.DOWN
BACK = DFSFlags.BACK
CROSS = DFSFlags.CROSS
LEAVE = DFSFlags.LEAVE
UP = DFSFlags.UP
MAXDEPTH = DFSFlags.MAXDEPTH
class GraphBase(Parsable):
def __init__(G, N: int, M: int, U: list[int], V: list[int],
deg: list[int], La: list[int], Ra: list[int],
Ua: list[int], Va: list[int], Ea: list[int], twin: list[int] = None):
G.N = N
'''The number of vertices.'''
G.M = M
'''The number of edges.'''
G.U = U
'''A list of source vertices in the original edge list.'''
G.V = V
'''A list of destination vertices in the original edge list.'''
G.deg = deg
'''deg[u] is the out degree of vertex u.'''
G.La = La
'''La[u] stores the start index of the list of adjacent vertices from u.'''
G.Ra = Ra
'''Ra[u] stores the stop index of the list of adjacent vertices from u.'''
G.Ua = Ua
'''Ua[i] = u for La[u] <= i < Ra[u], useful for backtracking.'''
G.Va = Va
'''Va[i] lists adjacent vertices to u for La[u] <= i < Ra[u].'''
G.Ea = Ea
'''Ea[i] lists the edge ids that start from u for La[u] <= i < Ra[u].
For undirected graphs, edge ids in range M<= e <2*M are edges from V[e-M] -> U[e-M].
'''
G.twin = twin if twin is not None else range(len(Ua))
'''twin[i] in undirected graphs stores index j of the same edge but with u and v swapped.'''
G.st: list[int] = None
G.order: list[int] = None
G.vis: list[int] = None
G.back: list[int] = None
G.tin: list[int] = None
def clear(G):
G.vis = G.back = G.tin = None
def prep_vis(G):
if G.vis is None: G.vis = u8f(G.N)
return G.vis
def prep_st(G):
if G.st is None: G.st = elist(G.N)
else: G.st.clear()
return G.st
def prep_order(G):
if G.order is None: G.order = elist(G.N)
else: G.order.clear()
return G.order
def prep_back(G):
if G.back is None: G.back = i32f(G.N, -2)
return G.back
def prep_tin(G):
if G.tin is None: G.tin = i32f(G.N, -1)
return G.tin
def _remove(G, a: int):
G.deg[u := G.Ua[a]] -= 1
G.Ra[u] = (r := G.Ra[u]-1)
G.Ua[a], G.Va[a], G.Ea[a] = G.Ua[r], G.Va[r], G.Ea[r]
G.twin[a], G.twin[r] = G.twin[r], G.twin[a]
G.twin[G.twin[a]] = a
G.twin[G.twin[r]] = r
def remove(G, a: int):
b = G.twin[a]; G._remove(a)
if a != b: G._remove(b)
def __len__(G) -> int: return G.N
def __getitem__(G, u): return view(G.Va, G.La[u], G.Ra[u])
def range(G, u): return range(G.La[u],G.Ra[u])
@overload
def distance(G) -> list[list[int]]: ...
@overload
def distance(G, s: int = 0) -> list[int]: ...
@overload
def distance(G, s: int, g: int) -> int: ...
def distance(G, s = None, g = None):
if s == None: return G.floyd_warshall()
else: return G.bfs(s, g)
def recover_path(G, s, t):
P = u32f(0)
while s != t: P.append(a := G.back[t]); t = G.Ua[a]
return P
def shortest_path(G, s: int, t: int):
if G.distance(s, t) >= inf: return None
P = G.recover_path(s, t)
P.reverse()
return P
@overload
def bfs(G, s: Union[int,list] = 0) -> list[int]: ...
@overload
def bfs(G, s: Union[int,list], g: int) -> int: ...
def bfs(G, s: int = 0, g: int = None):
S, Va, back, D = G.starts(s), G.Va, i32f(N := G.N, -1), [inf]*N
G.back, G.D = back, D
for u in S: D[u] = 0
que = Que(S)
while que:
nd = D[u := que.pop()]+1
if u == g: return nd-1
for i in G.range(u):
if chmin(D, v := Va[i], nd): back[v] = i; que.push(v)
return D if g is None else inf
def floyd_warshall(G) -> list[list[int]]:
G.D = D = [[inf]*G.N for _ in range(G.N)]
for u in range(G.N): D[u][u] = 0
for i in range(len(G.Ua)): D[G.Ua[i]][G.Va[i]] = 1
for k, Dk in enumerate(D):
for Di in D:
if (Dik := Di[k]) == inf: continue
for j in range(G.N):
chmin(Di, j, Dik+Dk[j])
return D
def find_cycle_indices(G, s: Union[int, None] = None):
Ea, Ua, Va, vis, back = G.Ea, G. Ua, G.Va, u8f(N := G.N), u32f(N, i32_max)
G.vis, G.back, st = vis, back, elist(N)
for s in G.starts(s):
if vis[s]: continue
st.append(s)
while st:
if not vis[u := st.pop()]:
st.append(u)
vis[u], pe = 1, Ea[j] if (j := back[u]) != i32_max else i32_max
for i in G.range(u):
if not vis[v := Va[i]]:
back[v] = i
st.append(v)
elif vis[v] == 1 and pe != Ea[i]:
I = u32f(1,i)
while v != u: I.append(i := back[u]), (u := Ua[i])
I.reverse()
return I
else:
vis[u] = 2
# check for self loops
for i in range(len(Ua)):
if Ua[i] == Va[i]:
return u32f(1,i)
def find_cycle(G, s: Union[int, None] = None):
if I := G.find_cycle_indices(s): return [G.Ua[i] for i in I]
def find_cycle_edge_ids(G, s: Union[int, None] = None):
if I := G.find_cycle_indices(s): return [G.Ea[i] for i in I]
def find_minimal_cycle(G, s=0):
D, par, que, Va = u32f(N := G.N, u32_max), i32f(N, -1), Que([s]), G.Va
D[s] = 0
while que:
for i in G.range(u := que.pop()):
if (v := Va[i]) == s: # Found cycle back to start
cycle = [u]
while u != s: cycle.append(u := par[u])
return cycle
if D[v] < u32_max: continue
D[v], par[v] = D[u]+1, u; que.push(v)
def dfs_topo(G, s: Union[int,list] = None) -> list[int]:
'''Returns lists of indices i where Ua[i] -> Va[i] are edges in order of top down discovery'''
vis, st, order = G.prep_vis(), G.prep_st(), G.prep_order()
for s in G.starts(s):
if vis[s]: continue
vis[s] = 1; st.append(s)
while st:
for i in G.range(st.pop()):
if vis[v := G.Va[i]]: continue
vis[v] = 1; order.append(i); st.append(v)
return order
def dfs(G, s: Union[int,list] = None, /,
backtrack = False,
max_depth = None,
enter_fn: Callable[[int],None] = None,
leave_fn: Callable[[int],None] = None,
max_depth_fn: Callable[[int],None] = None,
down_fn: Callable[[int,int,int],None] = None,
back_fn: Callable[[int,int,int],None] = None,
forward_fn: Callable[[int,int,int],None] = None,
cross_fn: Callable[[int,int,int],None] = None,
up_fn: Callable[[int,int,int],None] = None):
I, time, vis, st, back, tin = G.La[:], -1, G.prep_vis(), G.prep_st(), G.prep_back(), G.prep_tin()
for s in G.starts(s):
if vis[s]: continue
back[s], tin[s] = -1, (time := time+1); st.append(s)
while st:
if vis[u := st[-1]] == 0:
vis[u] = 1
if enter_fn: enter_fn(u)
if max_depth is not None and len(st) > max_depth:
I[u] = G.Ra[u]
if max_depth_fn: max_depth_fn(u)
if (i := I[u]) < G.Ra[u]:
I[u] += 1
if (s := vis[v := G.Va[i]]) == 0:
back[v], tin[v] = i, (time := time+1); st.append(v)
if down_fn: down_fn(u,v,i)
elif back_fn and s == 1 and back[u] != G.twin[i]: back_fn(u,v,i)
elif (cross_fn or forward_fn) and s == 2:
if forward_fn and tin[u] < tin[v]: forward_fn(u,v,i)
elif cross_fn: cross_fn(u,v,i)
else:
vis[u] = 2; st.pop()
if backtrack: vis[u], I[u] = 0, G.La[u]
if leave_fn: leave_fn(u)
if up_fn and st: up_fn(u, st[-1], back[u])
def dfs_enter_leave(G, s: Union[int,list[int],None] = None) -> Sequence[tuple[DFSEvent,int]]:
N, I = G.N, G.La[:]
st, back, plst = elist(N), i32f(N,-2), PacketList(order := elist(2*N), N-1)
G.back, ENTER, LEAVE = back, int(DFSEvent.ENTER) << plst.shift, int(DFSEvent.LEAVE) << plst.shift
for s in G.starts(s):
if back[s] >= -1: continue
back[s] = -1
order.append(ENTER | s), st.append(s)
while st:
if (i := I[u := st[-1]]) < G.Ra[u]:
I[u] += 1
if back[v := G.Va[i]] >= -1: continue
back[v] = i; order.append(ENTER | v); st.append(v)
else:
order.append(LEAVE | u); st.pop()
return plst
def starts(G, s: Union[int,list[int],None] = None) -> list[int]:
if isinstance(s, int): return [s]
elif s is None: return range(G.N)
elif isinstance(s, list): return s
else: return list(s)
@classmethod
def compile(cls, N: int, M: int, shift: int = -1):
def parse(io: IOBase):
U, V = u32f(M), u32f(M)
for i in range(M): u, v = io.readints(); U[i], V[i] = u+shift, v+shift
return cls(N, U, V)
return parse
u32_max = (1<<32)-1
i32_max = (1<<31)-1
from array import array
def u8f(N: int, elm: int = 0): return array('B', (elm,))*N # unsigned char
def u32f(N: int, elm: int = 0): return array('I', (elm,))*N # unsigned int
def i32f(N: int, elm: int = 0): return array('i', (elm,))*N # signed int
def elist(hint: int) -> list: ...
try:
from __pypy__ import newlist_hint
except:
def newlist_hint(hint): return []
elist = newlist_hint
class PacketList(Sequence[tuple[int,int]]):
def __init__(lst, A: list[int], max1: int):
lst.A = A
lst.mask = (1 << (shift := (max1).bit_length())) - 1
lst.shift = shift
def __len__(lst): return lst.A.__len__()
def __contains__(lst, x: tuple[int,int]): return lst.A.__contains__(x[0] << lst.shift | x[1])
def __getitem__(lst, key) -> tuple[int,int]:
x = lst.A[key]
return x >> lst.shift, x & lst.mask
class Que:
def __init__(que, v = None): que.q = elist(v) if isinstance(v, int) else list(v) if v else []; que.h = 0
def push(que, item): que.q.append(item)
def pop(que): que.h = (h := que.h) + 1; return que.q[h]
def extend(que, items): que.q.extend(items)
def __getitem__(que, i: int): return que.q[que.h+i]
def __setitem__(que, i: int, v): que.q[que.h+i] = v
def __len__(que): return que.q.__len__() - que.h
def __hash__(que): return hash(tuple(que.q[que.h:]))
from typing import Generic
from typing import TypeVar
_S = TypeVar('S'); _T = TypeVar('T'); _U = TypeVar('U'); _T1 = TypeVar('T1'); _T2 = TypeVar('T2'); _T3 = TypeVar('T3'); _T4 = TypeVar('T4'); _T5 = TypeVar('T5'); _T6 = TypeVar('T6')
import sys
def list_find(lst: list, value, start = 0, stop = sys.maxsize):
try:
return lst.index(value, start, stop)
except:
return -1
class view(Generic[_T]):
__slots__ = 'A', 'l', 'r'
def __init__(V, A: list[_T], l: int = 0, r: int = 0): V.A, V.l, V.r = A, l, r
def __len__(V): return V.r - V.l
def __getitem__(V, i: int):
if 0 <= i < V.r - V.l: return V.A[V.l+i]
else: raise IndexError
def __setitem__(V, i: int, v: _T): V.A[V.l+i] = v
def __contains__(V, v: _T): return list_find(V.A, v, V.l, V.r) != -1
def set_range(V, l: int, r: int): V.l, V.r = l, r
def index(V, v: _T): return V.A.index(v, V.l, V.r) - V.l
def reverse(V):
l, r = V.l, V.r-1
while l < r: V.A[l], V.A[r] = V.A[r], V.A[l]; l += 1; r -= 1
def sort(V, /, *args, **kwargs):
A = V.A[V.l:V.r]; A.sort(*args, **kwargs)
for i,a in enumerate(A,V.l): V.A[i] = a
def pop(V): V.r -= 1; return V.A[V.r]
def append(V, v: _T): V.A[V.r] = v; V.r += 1
def popleft(V): V.l += 1; return V.A[V.l-1]
def appendleft(V, v: _T): V.l -= 1; V.A[V.l] = v;
def validate(V): return 0 <= V.l <= V.r <= len(V.A)
class IOBase:
@property
def char(io) -> bool: ...
@property
def writable(io) -> bool: ...
def __next__(io) -> str: ...
def write(io, s: str) -> None: ...
def readline(io) -> str: ...
def readtoken(io) -> str: ...
def readtokens(io) -> list[str]: ...
def readints(io) -> list[int]: ...
def readdigits(io) -> list[int]: ...
def readnums(io) -> list[int]: ...
def readchar(io) -> str: ...
def readchars(io) -> str: ...
def readinto(io, lst: list[str]) -> list[str]: ...
def readcharsinto(io, lst: list[str]) -> list[str]: ...
def readtokensinto(io, lst: list[str]) -> list[str]: ...
def readintsinto(io, lst: list[int]) -> list[int]: ...
def readdigitsinto(io, lst: list[int]) -> list[int]: ...
def readnumsinto(io, lst: list[int]) -> list[int]: ...
def wait(io): ...
def flush(io) -> None: ...
def line(io) -> list[str]: ...
GraphBase.recover_path_edge_ids = recover_path_edge_ids
def shortest_path_edge_ids(G: 'GraphBase', s: int, t: int):
if G.distance(s, t) >= inf: return None
P = recover_path_edge_ids(G, s, t); P.reverse()
return P
GraphBase.shortest_path_edge_ids = shortest_path_edge_ids