Tifa's CP Library

:heavy_check_mark: ssp (src/code/graph/ssp.hpp)

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#ifndef TIFALIBS_GRAPH_DINIC
#define TIFALIBS_GRAPH_DINIC

#include "../util/util.hpp"

namespace tifa_libs::graph {

template <class EW = u32, class EC = i32>
class ssp {
  struct YYZ {
    u32 to;
    EW w;
    EC c;
    u32 inv;
  };
  const u32 N, S, T;
  vec<i64> dis;
  vec<EW> flow;
  vecpt<u32> pre;

  bool spfa(u64 inflow) {
    dis = vec<i64>(N, std::numeric_limits<i64>::max() / 2 - 1);
    vecb inq(N);
    std::queue<u32> q({S});
    dis[S] = 0, flow[S] = EW(inflow), flow[T] = 0, inq[S] = 1;
    while (!q.empty()) {
      u32 u = q.front();
      q.pop(), inq[u] = 0;
      for (u32 i = 0; i < e[u].size(); ++i) {
        auto v = e[u][i];
        if (dis[u] + v.c < dis[v.to] && v.w) {
          dis[v.to] = dis[u] + v.c;
          if (!inq[v.to]) q.push(v.to), inq[v.to] = 1;
          flow[v.to] = std::min(flow[u], v.w);
          pre[v.to] = {u, i};
        }
      }
    }
    return flow[T];
  }
  constexpr void update(u64& retflow, i64& retcost) {
    retflow += flow[T];
    for (u32 u = T; u != S; u = pre[u].first) {
      e[pre[u].first][pre[u].second].w -= flow[T];
      e[u][e[pre[u].first][pre[u].second].inv].w += flow[T];
      retcost += i64(flow[T]) * e[pre[u].first][pre[u].second].c;
    }
  }

 public:
  vvec<YYZ> e;

  constexpr ssp(u32 n, u32 s, u32 t) : N(n), S(s), T(t), dis(), flow(n), pre(n), e(n) {}

  constexpr void add(u32 u, u32 v, EW w, EC c) {
    u32 temu = u32(e[u].size()), temv = u32(e[v].size());
    e[u].push_back({v, w, c, temv}), e[v].push_back({u, 0, -c, temu});
  }
  constexpr std::pair<u64, i64> operator()(u64 inflow = std::numeric_limits<u64>::max()) {
    u64 retflow = 0;
    i64 retcost = 0;
    bool flag = inflow == std::numeric_limits<EW>::max();
    while (spfa(flag ? inflow : inflow - retflow)) update(retflow, retcost);
    return {retflow, retcost};
  }
};

}  // namespace tifa_libs::graph

#endif
#line 1 "src/code/graph/ssp.hpp"



#line 1 "src/code/util/util.hpp"



#include <bits/stdc++.h>

template <class T>
constexpr T abs(T x) { return x < 0 ? -x : x; }

using i8 = int8_t;
using i16 = int16_t;
using i32 = int32_t;
using i64 = int64_t;
using i128 = __int128_t;
using isz = ptrdiff_t;

using u8 = uint8_t;
using u16 = uint16_t;
using u32 = uint32_t;
using u64 = uint64_t;
using u128 = __uint128_t;
using usz = size_t;

using f32 = float;
using f64 = double;
using f128 = long double;

template <class T>
using ptt = std::pair<T, T>;
template <class T>
using pt3 = std::tuple<T, T, T>;
template <class T>
using pt4 = std::tuple<T, T, T, T>;

template <class T, usz N>
using arr = std::array<T, N>;
template <class T>
using vec = std::vector<T>;
template <class T>
using vvec = vec<vec<T>>;
template <class T>
using v3ec = vec<vvec<T>>;
template <class U, class T>
using vecp = vec<std::pair<U, T>>;
template <class U, class T>
using vvecp = vvec<std::pair<U, T>>;
template <class T>
using vecpt = vec<ptt<T>>;
template <class T>
using vvecpt = vvec<ptt<T>>;

template <class T, class C = std::less<T>>
using pq = std::priority_queue<T, vec<T>, C>;
template <class T>
using pqg = std::priority_queue<T, vec<T>, std::greater<T>>;

using strn = std::string;
using strnv = std::string_view;

using vecu = vec<u32>;
using vvecu = vvec<u32>;
using v3ecu = v3ec<u32>;
using vecu64 = vec<u64>;
using vecb = vec<bool>;
using vvecb = vvec<bool>;

#ifdef ONLINE_JUDGE
#undef assert
#define assert(x) 42
#endif

using namespace std::literals;

constexpr i8 operator""_i8(unsigned long long x) { return (i8)x; }
constexpr i16 operator""_i16(unsigned long long x) { return (i16)x; }
constexpr i32 operator""_i32(unsigned long long x) { return (i32)x; }
constexpr i64 operator""_i64(unsigned long long x) { return (i64)x; }
constexpr isz operator""_iz(unsigned long long x) { return (isz)x; }

constexpr u8 operator""_u8(unsigned long long x) { return (u8)x; }
constexpr u16 operator""_u16(unsigned long long x) { return (u16)x; }
constexpr u32 operator""_u32(unsigned long long x) { return (u32)x; }
constexpr u64 operator""_u64(unsigned long long x) { return (u64)x; }
constexpr usz operator""_uz(unsigned long long x) { return (usz)x; }

inline const auto fn_0 = [](auto&&...) {};
inline const auto fn_is0 = [](auto x) { return x == 0; };


#line 5 "src/code/graph/ssp.hpp"

namespace tifa_libs::graph {

template <class EW = u32, class EC = i32>
class ssp {
  struct YYZ {
    u32 to;
    EW w;
    EC c;
    u32 inv;
  };
  const u32 N, S, T;
  vec<i64> dis;
  vec<EW> flow;
  vecpt<u32> pre;

  bool spfa(u64 inflow) {
    dis = vec<i64>(N, std::numeric_limits<i64>::max() / 2 - 1);
    vecb inq(N);
    std::queue<u32> q({S});
    dis[S] = 0, flow[S] = EW(inflow), flow[T] = 0, inq[S] = 1;
    while (!q.empty()) {
      u32 u = q.front();
      q.pop(), inq[u] = 0;
      for (u32 i = 0; i < e[u].size(); ++i) {
        auto v = e[u][i];
        if (dis[u] + v.c < dis[v.to] && v.w) {
          dis[v.to] = dis[u] + v.c;
          if (!inq[v.to]) q.push(v.to), inq[v.to] = 1;
          flow[v.to] = std::min(flow[u], v.w);
          pre[v.to] = {u, i};
        }
      }
    }
    return flow[T];
  }
  constexpr void update(u64& retflow, i64& retcost) {
    retflow += flow[T];
    for (u32 u = T; u != S; u = pre[u].first) {
      e[pre[u].first][pre[u].second].w -= flow[T];
      e[u][e[pre[u].first][pre[u].second].inv].w += flow[T];
      retcost += i64(flow[T]) * e[pre[u].first][pre[u].second].c;
    }
  }

 public:
  vvec<YYZ> e;

  constexpr ssp(u32 n, u32 s, u32 t) : N(n), S(s), T(t), dis(), flow(n), pre(n), e(n) {}

  constexpr void add(u32 u, u32 v, EW w, EC c) {
    u32 temu = u32(e[u].size()), temv = u32(e[v].size());
    e[u].push_back({v, w, c, temv}), e[v].push_back({u, 0, -c, temu});
  }
  constexpr std::pair<u64, i64> operator()(u64 inflow = std::numeric_limits<u64>::max()) {
    u64 retflow = 0;
    i64 retcost = 0;
    bool flag = inflow == std::numeric_limits<EW>::max();
    while (spfa(flag ? inflow : inflow - retflow)) update(retflow, retcost);
    return {retflow, retcost};
  }
};

}  // namespace tifa_libs::graph


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