Submission #291851

#	Time	Username	Problem	Language	Result	Execution time	Memory
291851		ant101	Tug of War (BOI15_tug)	C++14	48 / 100	513 ms	2772 KiB

tug

#include <iostream>
#include <algorithm>
#include <cstring>
#include <iomanip>
#include <fstream>
#include <cmath>
#include <vector>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <map>
#include <stack>
#include <queue>
#include <assert.h>
#include <limits>
#include <cstdio>
#include <complex>
using namespace std;

typedef long long ll;
typedef long double ld;
typedef double db;
typedef string str;

typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
#define mp make_pair
#define f first
#define s second

typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<ld> vd;
typedef vector<str> vs;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<pd> vpd;

#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rall(x) (x).rbegin(), (x).rend()
#define rsz resize
#define ins insert
#define ft front()
#define bk back()
#define pf push_front
#define pb push_back
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)

const int MOD = 1e9+7; // 998244353; // = (119<<23)+1
const int MX = 4e3+5;
const ll INF = 1e18;
const ld PI = 4*atan((ld)1);
const int dx[4] = {0,1,0,-1}, dy[4] = {1,0,-1,0};


namespace io {
    void setIn(string s) { freopen(s.c_str(),"r",stdin); }
    void setOut(string s) { freopen(s.c_str(),"w",stdout); }
    void setIO(string s = "") {
        ios_base::sync_with_stdio(0); cin.tie(0); // fast I/O
        // cin.exceptions(cin.failbit); // ex. throws exception when you try to read letter into int
        if (sz(s)) {
            setIn(s+".in");
            setOut(s+".out");
        } // for USACO
    }
}

using namespace io;

namespace input {
    template<class T> void re(complex<T>& x);
    template<class T1, class T2> void re(pair<T1,T2>& p);
    template<class T> void re(vector<T>& a);
    template<class T, size_t SZ> void re(array<T,SZ>& a);
    
    template<class T> void re(T& x) { cin >> x; }
    void re(double& x) { string t; re(t); x = stod(t); }
    void re(ld& x) { string t; re(t); x = stold(t); }
    template<class Arg, class... Args> void re(Arg& first, Args&... rest) {
        re(first); re(rest...);
    }
    
    template<class T> void re(complex<T>& x) { T a,b; re(a,b); x = cd(a,b); }
    template<class T1, class T2> void re(pair<T1,T2>& p) { re(p.f,p.s); }
    template<class T> void re(vector<T>& a) { F0R(i,sz(a)) re(a[i]); }
    template<class T, size_t SZ> void re(array<T,SZ>& a) { F0R(i,SZ) re(a[i]); }
}

namespace output {
    template<class T1, class T2> void pr(const pair<T1,T2>& x);
    template<class T, size_t SZ> void pr(const array<T,SZ>& x);
    template<class T> void pr(const vector<T>& x);
    template<class T> void pr(const set<T>& x);
    template<class T1, class T2> void pr(const map<T1,T2>& x);
    
    template<class T> void pr(const T& x) { cout << x; }
    template<class Arg, class... Args> void pr(const Arg& first, const Args&... rest) {
        pr(first); pr(rest...);
    }
    
    template<class T1, class T2> void pr(const pair<T1,T2>& x) {
        pr("{",x.f,", ",x.s,"}");
    }
    template<class T> void prContain(const T& x) {
        pr("{");
        bool fst = 1; for (const auto& a: x) pr(!fst?", ":"",a), fst = 0; // const needed for vector<bool>
        pr("}");
    }
    template<class T, size_t SZ> void pr(const array<T,SZ>& x) { prContain(x); }
    template<class T> void pr(const vector<T>& x) { prContain(x); }
    template<class T> void pr(const set<T>& x) { prContain(x); }
    template<class T1, class T2> void pr(const map<T1,T2>& x) { prContain(x); }
    
    void ps() { pr("\n"); }
    template<class Arg> void ps(const Arg& first) {
        pr(first); ps(); // no space at end of line
    }
    template<class Arg, class... Args> void ps(const Arg& first, const Args&... rest) {
        pr(first," "); ps(rest...); // print w/ spaces
    }
}

using namespace output;

using namespace input;

ll add(ll a, ll b) {
    a += b;
    if(a >= MOD) {
        a -= MOD;
    }
    return a;
}
ll sub(ll a, ll b) {
    a -= b;
    if(a < 0) {
        a += MOD;
    }
    return a;
}

ll mul(ll a, ll b) {
    return (a * b)%MOD;
}

void add_self(ll& a, ll b) {
    a = add(a, b);
}
void sub_self(ll& a, ll b) {
    a = sub(a, b);
}
void mul_self(ll& a, ll b) {
    a = mul(a, b);
}

ll N, K;

pl buckets[MX];
set<ll> r1[MX];
set<ll> r2[MX];
pl pref[MX];
ll skill[MX];
pair<ll, ll> cr1[MX], cr2[MX];
ll vis[MX];
ll dp[2][80010];
ll ind = 0;

/*
 ll lone = *(r1[i].begin());
 r1[i].clear();
 r2[pref[lone].s].erase(lone);
 if (r2[pref[lone].s].size() == 1) {
 <#statements#>
 }
*/



int main() {
    setIO();
    re(N, K);
    FOR (i, 1, 2*N+1) {
        re(pref[i].f, pref[i].s, skill[i]);
        r1[pref[i].f].insert(i);
        r2[pref[i].s].insert(i);
    }
    FOR (i, 1, N+1) {
        if (!sz(r1[i]) || !sz(r2[i])) {
            ps("NO");
            return 0;
        }
    }
    queue<pl> q;
    FOR (i, 1, N+1) {
        if (sz(r1[i]) == 1) {
            q.push({1, i});
        }
        if (sz(r2[i]) == 1) {
            q.push({2, i});
        }
    }
    ll currdiff = 0;
    while (!q.empty()) {
        pl todel = q.front();
        q.pop();
        if (todel.f == 1) {
            ll lone = *(r1[todel.s].begin());
            r1[todel.s].clear();
            r2[pref[lone].s].erase(lone);
            currdiff+=skill[lone];
            if (r2[pref[lone].s].size() == 1) {
                q.push({2, pref[lone].s});
            }
        } else {
            ll lone = *(r2[todel.s].begin());
            r2[todel.s].clear();
            r1[pref[lone].f].erase(lone);
            currdiff-=skill[lone];
            if (r1[pref[lone].f].size() == 1) {
                q.push({1, pref[lone].f});
            }
        }
    }
    FOR (i, 1, N+1) {
        if (r1[i].size() == 2) {
            cr1[i] = {*r1[i].begin(), *(--r1[i].end())};
        }
        if (r2[i].size() == 2) {
            cr2[i] = {*r2[i].begin(), *(--r2[i].end())};
        }
    }
    FOR (i, 1, N+1) {
        if (!vis[i] && r1[i].size() == 2) {
            ll diff1 = skill[cr1[i].f];
            ll curr = cr1[i].s;
            ll currarr = 1;
            while (curr != cr1[i].f) {
                if (currarr == 1) {
                    diff1-=skill[curr];
                    ll innd = pref[curr].s;
                    if (cr2[innd].f == curr) {
                        curr = cr2[innd].s;
                    } else {
                        curr = cr2[innd].f;
                    }
                    currarr = 2;
                } else {
                    diff1+=skill[curr];
                    ll innd = pref[curr].f;
                    if (cr1[innd].f == curr) {
                        curr = cr1[innd].s;
                    } else {
                        curr = cr1[innd].f;
                    }
                    currarr = 1;
                }
            }
            ll diff2 = skill[cr1[i].s];
            curr = cr1[i].f;
            currarr = 1;
            while (curr != cr1[i].s) {
                if (currarr == 1) {
                    diff2-=skill[curr];
                    ll innd = pref[curr].s;
                    if (cr2[innd].f == curr) {
                        curr = cr2[innd].s;
                    } else {
                        curr = cr2[innd].f;
                    }
                    vis[pref[curr].f] = true;
                    currarr = 2;
                } else {
                    diff2+=skill[curr];
                    ll innd = pref[curr].f;
                    if (cr1[innd].f == curr) {
                        curr = cr1[innd].s;
                    } else {
                        curr = cr1[innd].f;
                    }
//                    vis[innd] = true;
                    currarr = 1;
                }
            }
            vis[i] = true;
//            cout << ind << " " << i << "\n";
            buckets[ind++] = {diff1, diff2};
        }
    }
    dp[0][currdiff+40000] = 1;
    for (ll i = 0; i<ind; i++) {
        for (ll j = 0; j<80010; j++) {
            if (dp[0][j] != 1) {
                continue;
            }
            if (j+buckets[i].f < 0 || j+buckets[i].f > 80000) {
                
            } else {
                dp[1][j+buckets[i].f] = 1;
            }
            if (j+buckets[i].s < 0 || j+buckets[i].s > 80000) {
                
            } else {
                dp[1][j+buckets[i].s] = 1;
            }
        }
        for (ll j = 0; j<80010; j++) {
            dp[0][j] = dp[1][j];
            dp[1][j] = 0;
        }
    }
    ll best = 1e13;
    for (ll i = 0; i<80010; i++) {
        if (!dp[0][i]) {
            continue;
        }
        best = min(best, abs(i-40000));
    }
    if (best <= K) {
        cout << "YES" << "\n";
    } else {
        cout << "NO" << "\n";
    }
    return 0;
}

Compilation message (stderr)

tug.cpp: In function 'void io::setIn(std::string)':
tug.cpp:67:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   67 |     void setIn(string s) { freopen(s.c_str(),"r",stdin); }
      |                            ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
tug.cpp: In function 'void io::setOut(std::string)':
tug.cpp:68:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   68 |     void setOut(string s) { freopen(s.c_str(),"w",stdout); }
      |                             ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 18 / 18
• Subtask 2: 30 / 30
• Subtask 3: 0 / 23
• Subtask 4: 0 / 29