Submission #366992

#	Time	Username	Problem	Language	Result	Execution time	Memory
366992		gmyu	Tug of War (BOI15_tug)	C++14	71 / 100	1540 ms	12780 KiB

tug

/*
ID: USACO_template
LANG: C++
PROG: https://oj.uz/problem/view/BOI15_tug
*/
#include <iostream>  //cin , cout
#include <fstream>   //fin, fout
#include <stdio.h>   // scanf , pringf
#include <cstdio>
#include <algorithm> // sort , stuff
#include <stack>     // stacks
#include <queue>     // queues
#include <map>
#include <string>
#include <string.h>
#include <set>
#include <bitset>

using namespace std;

typedef pair<int, int>          pii;
typedef vector<int>             vi;     /// adjlist without weight
typedef vector<pii>             vii;    /// adjlist with weight
typedef vector<pair<int,pii>>   vpip;   /// edge with weight
typedef long long               ll;

#define mp  make_pair
#define ff  first
#define ss  second
#define pb  push_back
#define sz(x)   (int)(x).size()
#define adjread {int a, b; cin >> a >> b; adjlist[a].pb(b); adjlist[b].pb(a); }

const int MOD = 1e9+7;  // 998244353;
const int MX  = 2e5+5;   //
const ll  INF = 1e18;    //

#define MAXV 30007
#define MAXE 100007

const int xdir[4] = {1,0,-1,0}, ydir[4] = {0,1,0,-1}; /// 4 directions
struct NODE {
    int x, y;
    int val;
    int visited;
    bool operator< (NODE b) const { return (x == b.x) ? (y < b.y) : (x < b.x); }
};
struct EDGE {
    int from, to;
    ll weight;
    bool operator<(EDGE other) const { return weight < other.weight; }
};

bool debug;

int N, Klim;
vii adjlist[2][MAXV];
int marked[2][MAXV];
int s[2*MAXV];
int d0;

int roomCt;
int roomID[2][MAXV];
vii room[MAXV];
int deltaroom[MAXV];
void floodfill(int j, int i) {
    if(roomID[j][i] != 0) return;
    roomID[j][i] = roomCt;
    room[roomCt].pb(mp(j, i));
    for(auto x : adjlist[j][i]) {
        floodfill((j+1)%2, x.ff);
    }
}
int visited[2][MAXV];
int floodcal(int rm, pii v, int sel, int vis) {
    if(visited[v.ff][v.ss] == vis) return 0;
    visited[v.ff][v.ss] = vis;
    int d = adjlist[v.ff][v.ss][sel].ss * ( (v.ff==0)? 1 : (-1));
    if(debug) cout << v.ff << "," << v.ss << " assigned " << d << endl;
    int j1 = (v.ff+1)%2, i1 = adjlist[v.ff][v.ss][(sel+1)%2].ff;

    int sel1;
    if(adjlist[j1][i1][0].ff == v.ss && adjlist[j1][i1][0].ss == adjlist[v.ff][v.ss][(sel+1)%2].ss ) sel1 = 0;
    else sel1 = 1;
    d += floodcal(rm, mp(j1, i1), sel1, vis);
    return d;
}

int main() {
    debug = false;
    ios_base::sync_with_stdio(false); cin.tie(0);

    int i, j, k;
    int ans = 0;

    cin >> N >> Klim;
    for(i=1;i<=2*N;i++) {
        int a, b, c; cin >> a >> b >> c;
        adjlist[0][a].pb(mp(b,c)); adjlist[1][b].pb(mp(a,c));
    }

    /// remove single points
    bool hasSingle = true;
    while(hasSingle) {
        hasSingle = false;
        for(i=1; i<=N;i++) {
            for(j=0;j<2;j++) {
                if(marked[j][i]) continue;
                if(sz(adjlist[j][i])==0) {cout << "NO" << endl; exit(0);}
                if(sz(adjlist[j][i])==1) {
                    marked[j][i] = 1;
                    d0 += adjlist[j][i][0].ss * ((j==0)? 1 : (-1) );
                    int j1 = (j+1)%2, i1 = adjlist[j][i][0].ff;
                    for(k=0; k<sz(adjlist[j1][i1]) && adjlist[j1][i1][k].ff !=i; k++ );
                    adjlist[j1][i1].erase(adjlist[j1][i1].begin()+k);
                    hasSingle=true;
                    if(debug) cout << j << " " << i << " is single " << endl;
                }
            }
        }
    }

    /// assign cycle
    for(i=1;i<=N;i++)
        for(j=0;j<2;j++) {
            if(marked[j][i]) continue;
            if(roomID[j][i] != 0) continue;
            roomCt++;
            floodfill(j, i);
        }
    for(i=1; i<= roomCt; i++) {
        if(debug) cout << endl << "room " << i << endl;
        int d1 = floodcal(i, room[i][0], 0, 1);
        int d2 = floodcal(i, room[i][0], 1, 2);
        d0 += d1;
        deltaroom[i] = d2 - d1;
    }

    /// DP the assignment
    bitset<1200007> dp;
    int offset = 60001;
    dp[offset+d0]=1;
    if(debug) cout << d0 << endl;
    for(i=1;i<=roomCt;i++) {
        if(debug) cout << deltaroom[i] << endl;
        if(deltaroom[i]>=0) dp |= (dp << deltaroom[i]);
        else dp |= (dp >> (-deltaroom[i]));
    }
    for(i=0;i<=Klim;i++)
        if(dp[offset+i]==1 | dp[offset-i]==1)  {cout << "YES" << endl; exit(0);}


    cout << "NO" << endl;

}

Compilation message (stderr)

tug.cpp: In function 'int main()':
tug.cpp:150:24: warning: suggest parentheses around comparison in operand of '|' [-Wparentheses]
  150 |         if(dp[offset+i]==1 | dp[offset-i]==1)  {cout << "YES" << endl; exit(0);}
tug.cpp:94:9: warning: unused variable 'ans' [-Wunused-variable]
   94 |     int ans = 0;
      |         ^~~

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