oj.uz

Submission #318482

# Submission time Handle Problem Language Result Execution time Memory
318482 2020-11-02T05:33:38 Z jhnah917 Alternating Current (BOI18_alternating) C++14
0 / 100
 164 ms 13916 KB 
#include <bits/stdc++.h>
#define x first
#define y second
#define all(v) v.begin(), v.end()
#define compress(v) sort(all(v)), v.erase(unique(all(v)), v.end())
using namespace std;

typedef long long ll;

int par[101010];
vector<int> g[101010];
int find(int v){ return v == par[v] ? v : par[v] = find(par[v]); }
void merge(int pa, int ch){ pa = find(pa); ch = find(ch); if(pa != ch) par[ch] = pa; }

struct Seg{
    int tree[1 << 18], tmp[1 << 18], n;
    void init(int _n){ n = _n; memset(tree, 0, sizeof tree); memset(tmp, 0, sizeof tree); }
    void push(int node, int s, int e){
        if(!tmp[node]) return;
        tree[node] += tmp[node];
        if(s != e){
            tmp[node << 1] += tmp[node];
            tmp[node << 1 | 1] += tmp[node];
        }
        tmp[node] = 0;
    }
    void update(int node, int s, int e, int l, int r, int v){
        push(node, s, e);
        if(r < s || e < l) return;
        if(l <= s && e <= r){
            tmp[node] += v; push(node, s, e);
            return;
        }
        int m = s + e >> 1;
        update(node << 1, s, m, l, r, v);
        update(node << 1 | 1, m+1, e, l, r, v);
        tree[node] = min(tree[node << 1], tree[node << 1 | 1]);
    }
    int query(int node, int s, int e, int l, int r){
        push(node, s, e);
        if(r < s || e < l) return 1e9;
        if(l <= s && e <= r) return tree[node];
        int m = s + e >> 1;
        int t1 = query(node << 1, s, m, l, r);
        int t2 = query(node << 1 | 1, m+1, e, l, r);
        return min(t1, t2);
    }
    void update(int s, int e, int x){
        int S = s, E = e;
        if(E >= n) E -= n;
        if(S <= E) update(1, 0, n-1, S, E, x);
        else update(1, 0, n-1, 0, E, x), update(1, 0, n-1, S, n-1, x);
    }
    int query(int s, int e){ return query(1, 0, n-1, s, e); }
} seg[2];

struct Info{
    int s, e, x, eli, color;
    Info() : Info(0, 0, 0) {}
    Info(int s, int e, int x) : s(s), e(e), x(x), eli(-1), color(-1) {}
    bool operator < (const Info &t) const { return make_pair(s, -e) < make_pair(t.s, -t.e); }
};

int n, m, ed, ed_idx;
Info a[101010];
vector<Info> v;

void calc_elimination(){
    deque<Info> dq;
    sort(a+1, a+m+1);
    for(int i=1; i<=m; i++){
        if(dq.empty() || dq.back().e < a[i].e) dq.push_back(a[i]);
        else a[i].eli = dq.back().x;
    }
    while(dq.size() && dq.front().e <= ed) a[dq[0].x].eli = ed_idx, dq.pop_front();
    for(auto i : dq) v.push_back(i);
    
    iota(par, par+101010, 0);
    for(int i=1; i<=m; i++) if(a[i].eli != -1) merge(a[i].eli, a[i].x);
    for(int i=1; i<=m; i++){
        if(a[i].eli != -1) a[i].eli = find(a[i].x), g[a[i].eli].push_back(a[i].x);
        else g[a[i].x].push_back(a[i].x);
    }
}

bool eval(){
    int t1 = seg[0].query(0, n-1);
    int t2 = seg[1].query(0, n-1);
    return t1 > 0 && t2 > 0;
}

void even(){
    seg[0].init(n); seg[1].init(n);
    
    for(int i=0; i<v.size(); i++) a[v[i].x].color = i % 2;
    for(int i=1; i<=m; i++) if(a[i].color == -1) a[i].color = !a[a[i].eli].color;
    
    for(int i=1; i<=m; i++){
        seg[a[i].color].update(a[i].s, a[i].e, 1);
    }
    if(eval()){
        for(int i=1; i<=m; i++) cout << a[i].color;
    }
    else cout << "impossible";
}

void odd(){
    seg[0].init(n); seg[1].init(n);
    for(int i=0; i<v.size(); i++) a[v[i].x].color = i % 2;
    for(int i=1; i<=m; i++) if(a[i].color == -1) a[i].color = !a[a[i].eli].color;
    for(int i=1; i<=m; i++){
        seg[a[i].color].update(a[i].s, a[i].e, 1);
    }
    if(eval()){ for(int j=1; j<=m; j++) cout << a[j].color; return; }
    
    for(int i=0; i<v.size(); i++){
        for(auto j : g[v[i].x]){
            seg[a[j].color].update(a[j].s, a[j].e, -1);
            a[j].color ^= 1;
            seg[a[j].color].update(a[j].s, a[j].e, 1);
        }
        if(eval()){ for(int j=1; j<=m; j++) cout << a[j].color; return; }
    }
    cout << "impossible";
}

int main(){
    ios_base::sync_with_stdio(false); cin.tie(nullptr);
    cin >> n >> m;
    for(int i=1; i<=m; i++){
        int s, e; cin >> s >> e; s--; e--;
        if(s > e){
            if(ed < e) ed = e, ed_idx = i;
            e += n;
        }
        a[i] = {s, e, i};
    }
    calc_elimination();
    sort(a+1, a+m+1, [](Info a, Info b){ return a.x < b.x; });
    if(v.size() % 2 == 0) even();
    else odd();
}

Compilation message

alternating.cpp: In member function 'void Seg::update(int, int, int, int, int, int)':
alternating.cpp:34:19: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   34 |         int m = s + e >> 1;
      |                 ~~^~~
alternating.cpp: In member function 'int Seg::query(int, int, int, int, int)':
alternating.cpp:43:19: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   43 |         int m = s + e >> 1;
      |                 ~~^~~
alternating.cpp: In function 'void even()':
alternating.cpp:95:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Info>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   95 |     for(int i=0; i<v.size(); i++) a[v[i].x].color = i % 2;
      |                  ~^~~~~~~~~
alternating.cpp: In function 'void odd()':
alternating.cpp:109:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Info>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  109 |     for(int i=0; i<v.size(); i++) a[v[i].x].color = i % 2;
      |                  ~^~~~~~~~~
alternating.cpp:116:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Info>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  116 |     for(int i=0; i<v.size(); i++){
      |                  ~^~~~~~~~~

Subtask #1
0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 9196 KB Output is correct
2 Correct 6 ms 9196 KB Output is correct
3 Correct 6 ms 9196 KB Output is correct
4 Correct 6 ms 9196 KB Output is correct
5 Correct 6 ms 9196 KB Output is correct
6 Correct 6 ms 9196 KB Output is correct
7 Correct 6 ms 9196 KB Output is correct
8 Correct 6 ms 9196 KB Output is correct
9 Correct 6 ms 9196 KB Output is correct
10 Correct 6 ms 9196 KB Output is correct
11 Correct 6 ms 9196 KB Output is correct
12 Correct 6 ms 9196 KB Output is correct
13 Correct 6 ms 9196 KB Output is correct
14 Correct 6 ms 9196 KB Output is correct
15 Incorrect 6 ms 9196 KB 'impossible' claimed, but there is a solution
16 Halted 0 ms 0 KB -

Subtask #2
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 9196 KB Output is correct
2 Correct 6 ms 9196 KB Output is correct
3 Correct 6 ms 9196 KB Output is correct
4 Correct 6 ms 9196 KB Output is correct
5 Correct 6 ms 9196 KB Output is correct
6 Correct 6 ms 9196 KB Output is correct
7 Correct 6 ms 9196 KB Output is correct
8 Correct 6 ms 9196 KB Output is correct
9 Correct 6 ms 9196 KB Output is correct
10 Correct 6 ms 9196 KB Output is correct
11 Correct 6 ms 9196 KB Output is correct
12 Correct 6 ms 9196 KB Output is correct
13 Correct 6 ms 9196 KB Output is correct
14 Correct 6 ms 9196 KB Output is correct
15 Incorrect 6 ms 9196 KB 'impossible' claimed, but there is a solution
16 Halted 0 ms 0 KB -

Subtask #3
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 9196 KB Output is correct
2 Correct 6 ms 9196 KB Output is correct
3 Correct 6 ms 9196 KB Output is correct
4 Correct 6 ms 9196 KB Output is correct
5 Correct 6 ms 9196 KB Output is correct
6 Correct 6 ms 9196 KB Output is correct
7 Correct 6 ms 9196 KB Output is correct
8 Correct 6 ms 9196 KB Output is correct
9 Correct 6 ms 9196 KB Output is correct
10 Correct 6 ms 9196 KB Output is correct
11 Correct 6 ms 9196 KB Output is correct
12 Correct 6 ms 9196 KB Output is correct
13 Correct 6 ms 9196 KB Output is correct
14 Correct 6 ms 9196 KB Output is correct
15 Incorrect 6 ms 9196 KB 'impossible' claimed, but there is a solution
16 Halted 0 ms 0 KB -

Subtask #4
0 / 19.0

# Verdict Execution time Memory Grader output
1 Correct 38 ms 10676 KB Output is correct
2 Correct 6 ms 9196 KB Output is correct
3 Correct 100 ms 10088 KB Output is correct
4 Correct 48 ms 10216 KB Output is correct
5 Correct 94 ms 13272 KB Output is correct
6 Correct 164 ms 12636 KB Output is correct
7 Correct 84 ms 11424 KB Output is correct
8 Correct 9 ms 9324 KB Output is correct
9 Correct 7 ms 9216 KB Output is correct
10 Correct 102 ms 13404 KB Output is correct
11 Correct 71 ms 11744 KB Output is correct
12 Correct 75 ms 10980 KB Output is correct
13 Correct 7 ms 9196 KB Output is correct
14 Correct 6 ms 9196 KB Output is correct
15 Correct 88 ms 10980 KB Output is correct
16 Correct 105 ms 13412 KB Output is correct
17 Correct 146 ms 10976 KB Output is correct
18 Correct 103 ms 10716 KB Output is correct
19 Correct 13 ms 9324 KB Output is correct
20 Incorrect 122 ms 13916 KB 'impossible' claimed, but there is a solution

Subtask #5
0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 9196 KB Output is correct
2 Correct 6 ms 9196 KB Output is correct
3 Correct 6 ms 9196 KB Output is correct
4 Correct 6 ms 9196 KB Output is correct
5 Correct 6 ms 9196 KB Output is correct
6 Correct 6 ms 9196 KB Output is correct
7 Correct 6 ms 9196 KB Output is correct
8 Correct 6 ms 9196 KB Output is correct
9 Correct 6 ms 9196 KB Output is correct
10 Correct 6 ms 9196 KB Output is correct
11 Correct 6 ms 9196 KB Output is correct
12 Correct 6 ms 9196 KB Output is correct
13 Correct 6 ms 9196 KB Output is correct
14 Correct 6 ms 9196 KB Output is correct
15 Incorrect 6 ms 9196 KB 'impossible' claimed, but there is a solution
16 Halted 0 ms 0 KB -