Submission #722456

#	Time	Username	Problem	Language	Result	Execution time	Memory
722456		definitelynotmee	Seats (IOI18_seats)	C++17	100 / 100	2587 ms	72020 KiB

seats

#include "seats.h"
#include <bits/stdc++.h>
#define ff first
#define ss second
#define all(x) x.begin(), x.end()
using namespace std;
using ll = long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
template<typename T>
using matrix = vector<vector<T>>;
int n, m;

vector<int> v, rev;

inline int translate(int x, int y){
    return m*x+y;
}

inline pii detranslate(int id){
    return {id/m,id%m};
}

struct SegTree{
    struct seg{
        int mn, ct, sum;

        inline seg operator+(seg b){

            b.sum+=sum;
            b.mn+=sum;

            if(mn == b.mn)
                b.ct+=ct;
            if(mn < b.mn){
                b.ct = ct;
                b.mn = mn;
            }

            return b;
        }
    };

    vector<seg> tree;

    int q, val, sz;
    
    void build(int id, int l, int r){
        if(l == r){
            tree[id] = {0,1,0};
            return;
        }

        int e = id*2+1, d = id*2+2, m = (l+r)>>1;
        build(e,l,m);
        build(d,m+1,r);

        tree[id] = tree[e]+tree[d];
    }

    SegTree(int n = 1){
        tree.resize(4*n+4);
        sz = n;
        build(0,0,sz-1);
    }

    void update(int id, int l, int r){
        if(l > q || r < q)
            return;
        if(q <= l && r <= q){
            tree[id].mn+=val;
            tree[id].sum+=val;
            return;
        }

        int e = id*2+1, d = id*2+2, m = (l+r)>>1;
        update(e,l,m);
        update(d,m+1,r);
        tree[id] = tree[e] + tree[d];
    }    

    inline void makeupd(int l, int v){
        val = v;
        q = l;
        update(0,0,sz-1);
    }
} st;


inline void update(int x, int y, int type = 1){
    vector<int> vals;

    int dx[] = {0,0,1,1}, dy[] = {0,1,0,1};

    for(int i = 0; i < 4; i++){
        int xi = x+dx[i], yi = y + dy[i];

        if(xi < n && yi < m && xi >=0 && yi >= 0){
            vals.push_back(v[translate(xi,yi)]);
        }
    }
    sort(all(vals));

    int summing[] = {1,-1,1,-1};
    // cout << x << ' ' << y << endl;
    for(int i = 0; i < vals.size();i++){
        // cout << "update " << vals[i] << ' ' << n*m-1 << " => " << summing[i]*type << endl; 
        st.makeupd(vals[i],summing[i]*type);
    }
}

void give_initial_chart(int H, int W, std::vector<int> R, std::vector<int> C) {
    //cout << 'a' << endl;
    
    n = H;
    m = W;
    v = vector<int>(n*m);
    rev = vector<int>(n*m);

    for(int i = 0; i < n*m; i++){
        v[R[i]*m+C[i]] = i;
        rev[i] = R[i]*m+C[i];
    }
    st = SegTree(n*m);

    for(int x = -1; x < n; x++){
        for(int y = -1; y < m; y++){
            update(x,y);
        }
    }

}

int swap_seats(int a, int b) {
    array<pii,2> c({detranslate(rev[a]), detranslate(rev[b])});
    int dx[] = {0,0,-1,-1};
    int dy[] = {0,-1,-1,0};


    for(int i = 0; i < 4; i ++){
        for(int j = 0; j < 2; j++){
            int x = c[j].ff + dx[i], y = c[j].ss + dy[i];
            update(x,y,-1);
        }
    }

    swap(v[rev[a]],v[rev[b]]);
    swap(rev[a],rev[b]);

    for(int i = 0; i < 4; i ++){
        for(int j = 0; j < 2; j++){
            int x = c[j].ff + dx[i], y = c[j].ss + dy[i];
            update(x,y,1);
        }
    }

    //cout << "-> " << st.tree[0].mn << ' ' << st.tree[0].ct << '\n';
    return st.tree[0].ct;
}

Compilation message (stderr)

seats.cpp: In function 'void update(int, int, int)':
seats.cpp:106:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  106 |     for(int i = 0; i < vals.size();i++){
      |                    ~~^~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 6 / 6
• Subtask 3: 20 / 20
• Subtask 4: 6 / 6
• Subtask 5: 33 / 33
• Subtask 6: 30 / 30