oj.uz

Submission #1058626

# Submission time Handle Problem Language Result Execution time Memory
1058626 2024-08-14T11:36:31 Z otarius Alternating Current (BOI18_alternating) C++17
0 / 100
 80 ms 14820 KB 
#include <bits/stdc++.h>
#include <bits/extc++.h>
using namespace __gnu_pbds;
using namespace std;

// #pragma GCC optimize("Ofast")
// #pragma GCC optimize ("unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#define ff first
#define sc second
#define pb push_back
#define ll long long
#define pll pair<ll, ll>
#define pii pair<int, int>
#define ull unsigned long long
#define all(x) (x).begin(),(x).end()

// #define int long long
// #define int unsigned long long

// #define ordered_set(T) tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>
// #define ordered_multiset(T) tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>

void open_file(string filename) {
    freopen((filename + ".in").c_str(), "r", stdin);
    freopen((filename + ".out").c_str(), "w", stdout);
}

// const ll mod = 1e9 + 7;
// const ll mod = 998244353;

const ll inf = 1e9;
const ll biginf = 1e18;
const int maxN = 1e5 + 25;

int par[maxN];
vector<int> g[maxN];
void make_set() {
    for (int i = 0; i <= maxN; i++) par[i] = i;
}
int find_set(int v) {
    if (v == par[v])
        return v;
    return par[v] = find_set(par[v]);
}
void union_set(int x, int y) {
    x = find_set(x);
    y = find_set(y);
    if (x != y) par[y] = x;
}

struct segtree {
    int t[4 * maxN], lazy[4 * maxN], n;
    void init(int _n) {
        n = _n;
        for (int i = 0; i < 4 * maxN; i++)
            t[i] = lazy[i] = 0;
    }
    
    void prop(int v, int tl, int tr) {
        if (!lazy[v]) return;
        t[v] += lazy[v];
        if (tl != tr) {
            lazy[2 * v] += lazy[v];
            lazy[2 * v + 1] += lazy[v];
        } lazy[v] = 0;
    }
    
    void update(int v, int tl, int tr, int l, int r, int val) {
        prop(v, tl, tr);
        if (r < tl || tr < l) return;
        if (l <= tl && tr <= r) {
            lazy[v] += val;
            prop(v, tl, tr);
            return;
        } int tm = (tl + tr) / 2;
        update(2 * v, tl, tm, l, r, val);
        update(2 * v + 1, tm + 1, tr, l, r, val);
        t[v] = min(t[2 * v], t[2 * v + 1]);
    }
    
    int query(int v, int tl, int tr, int l, int r) {
        prop(v, tl, tr);
        if (l > r) return -inf;
        if (tl == l && tr == r)
            return t[v];
        int tm = (tl + tr) / 2;
        return min(query(2 * v, tl, tm, l, min(r, tm)),
                   query(2 * v + 1, tm + 1, tr, max(l, tm + 1), r));
    }
    
    void update(int l, int r, int val) {
        if (r > n) r -= n;
        if (l <= r) {
            update(1, 1, n, l, r, val);
        }
        else {
            update(1, 1, n, l, n, val);
            update(1, 1, n, 1, r, val);
        }
    }
    
    int eval() {
        return query(1, 1, n, 1, n);
    }
} seg[2];
bool check() {
    return (seg[0].eval() > 0 && seg[1].eval() > 0);
}

struct line {
    int x, y, id, cl, clr;
    line() {
        
    }
    line(int _x, int _y, int _id) {
        x = _x; y = _y; id = _id; cl = clr = -1;
    }
    bool operator<(const line &p) {
        return make_pair(x, -y) < make_pair(p.x, -p.y);
    }
} arr[maxN];
bool comp(line a, line b) {
    return a.id < b.id;
}

vector<line> good;
int n, m, mx, mxi, cld[maxN];
void elim() {
    deque<line> dq;
    sort(arr + 1, arr + m + 1);
    for (int i = 1; i <= n; i++) {
        if (dq.empty() || dq.back().y < arr[i].y) dq.push_back(arr[i]);
        else cld[arr[i].id] = dq.back().id;
    } while (dq.size() && dq.front().y <= mx) {
        cld[dq.front().id] = mxi; dq.pop_front();
    } for (line x : dq) good.pb(x);
    for (int i = 1; i <= m; i++)
        if (cld[arr[i].id]) arr[i].cl = cld[arr[i].id];
    make_set();
    for (int i = 1; i <= m; i++)
        if (arr[i].cl != -1) union_set(arr[i].cl, arr[i].id);
    for (int i = 1; i <= m; i++) {
        if (arr[i].cl != -1) {
            arr[i].cl = find_set(arr[i].id);
            g[arr[i].cl].pb(arr[i].id);
        } else g[arr[i].id].pb(arr[i].id);
    }
}
void even() {
    for (int i = 0; i < good.size(); i++)
        arr[good[i].id].clr = i % 2;
    for (int i = 1; i <= m; i++)
        if (arr[i].clr == -1) arr[i].clr = (arr[arr[i].cl].clr ^ 1);
    for (int i = 1; i <= m; i++) {
        seg[arr[i].clr].update(arr[i].x, arr[i].y, 1);
    }
    if (check()) {
        for (int i = 1; i <= m; i++)
            cout << arr[i].clr;
    } else {
        cout << "impo2ssible";
    } exit(0);
}
void odd() {
    for (int i = 0; i < good.size(); i++)
        arr[good[i].id].clr = i % 2;
    for (int i = 1; i <= m; i++)
        if (arr[i].clr == -1) arr[i].clr = (arr[arr[i].cl].clr ^ 1);
    for (int i = 1; i <= m; i++)
        seg[arr[i].clr].update(arr[i].x, arr[i].y, 1);
    if (check()) {
        for (int i = 1; i <= m; i++)
            cout << arr[i].clr;
        exit(0);
    } for (int i = 0; i < good.size(); i++) {
        for (int j : g[good[i].id]) {
            seg[arr[j].clr].update(arr[j].x, arr[j].y, -1);
            arr[j].clr ^= 1;
            seg[arr[j].clr].update(arr[j].x, arr[j].y, 1);
        } if (check()) {
            for (int j = 1; j <= m; j++)
                cout << arr[j].clr;
            exit(0);
        }
    } cout << "impossible";
    exit(0);
}
void solve() {
    cin >> n >> m;
    seg[0].init(n); seg[1].init(n);
    for (int i = 1; i <= m; i++) {
        int l, r; cin >> l >> r;
        if (l > r) {
            if (mx < r) {
                mx = r; mxi = i;
            } r += n;
        } arr[i] = {l, r, i};
    } elim();
    sort(arr + 1, arr + m + 1, comp);
    if (good.size() % 2 == 0) even();
    else odd();
}
int32_t main() { 
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
    
    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
        cout << '\n';
    }
    return 0;
}

Compilation message

alternating.cpp: In function 'void even()':
alternating.cpp:152:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<line>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  152 |     for (int i = 0; i < good.size(); i++)
      |                     ~~^~~~~~~~~~~~~
alternating.cpp: In function 'void odd()':
alternating.cpp:167:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<line>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  167 |     for (int i = 0; i < good.size(); i++)
      |                     ~~^~~~~~~~~~~~~
alternating.cpp:177:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<line>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  177 |     } for (int i = 0; i < good.size(); i++) {
      |                       ~~^~~~~~~~~~~~~
alternating.cpp: In function 'void open_file(std::string)':
alternating.cpp:26:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |     freopen((filename + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
alternating.cpp:27:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |     freopen((filename + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
alternating.cpp: In function 'void make_set()':
alternating.cpp:40:44: warning: iteration 100025 invokes undefined behavior [-Waggressive-loop-optimizations]
   40 |     for (int i = 0; i <= maxN; i++) par[i] = i;
      |                                     ~~~~~~~^~~
alternating.cpp:40:23: note: within this loop
   40 |     for (int i = 0; i <= maxN; i++) par[i] = i;
      |                     ~~^~~~~~~

Subtask #1
0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 11612 KB Output is correct
2 Correct 1 ms 11612 KB Output is correct
3 Correct 1 ms 11612 KB Output is correct
4 Correct 1 ms 11612 KB Output is correct
5 Correct 2 ms 11612 KB Output is correct
6 Correct 1 ms 11612 KB Output is correct
7 Correct 1 ms 11612 KB Output is correct
8 Correct 2 ms 11608 KB Output is correct
9 Correct 1 ms 11612 KB Output is correct
10 Correct 1 ms 11612 KB Output is correct
11 Incorrect 1 ms 11612 KB impo2ssible is not a string of length exactly 7
12 Halted 0 ms 0 KB -

Subtask #2
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 11612 KB Output is correct
2 Correct 1 ms 11612 KB Output is correct
3 Correct 1 ms 11612 KB Output is correct
4 Correct 1 ms 11612 KB Output is correct
5 Correct 2 ms 11612 KB Output is correct
6 Correct 1 ms 11612 KB Output is correct
7 Correct 1 ms 11612 KB Output is correct
8 Correct 2 ms 11608 KB Output is correct
9 Correct 1 ms 11612 KB Output is correct
10 Correct 1 ms 11612 KB Output is correct
11 Incorrect 1 ms 11612 KB impo2ssible is not a string of length exactly 7
12 Halted 0 ms 0 KB -

Subtask #3
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 11612 KB Output is correct
2 Correct 1 ms 11612 KB Output is correct
3 Correct 1 ms 11612 KB Output is correct
4 Correct 1 ms 11612 KB Output is correct
5 Correct 2 ms 11612 KB Output is correct
6 Correct 1 ms 11612 KB Output is correct
7 Correct 1 ms 11612 KB Output is correct
8 Correct 2 ms 11608 KB Output is correct
9 Correct 1 ms 11612 KB Output is correct
10 Correct 1 ms 11612 KB Output is correct
11 Incorrect 1 ms 11612 KB impo2ssible is not a string of length exactly 7
12 Halted 0 ms 0 KB -

Subtask #4
0 / 19.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 12256 KB Output is correct
2 Correct 2 ms 11608 KB Output is correct
3 Correct 42 ms 12052 KB Output is correct
4 Correct 21 ms 12120 KB Output is correct
5 Correct 51 ms 14544 KB Output is correct
6 Correct 80 ms 13904 KB Output is correct
7 Correct 45 ms 12988 KB Output is correct
8 Correct 3 ms 11608 KB Output is correct
9 Correct 2 ms 11612 KB Output is correct
10 Correct 54 ms 14820 KB Output is correct
11 Correct 45 ms 13400 KB Output is correct
12 Correct 50 ms 12252 KB Output is correct
13 Correct 1 ms 11612 KB Output is correct
14 Incorrect 2 ms 11612 KB impo2ssible is not a string of length exactly 26
15 Halted 0 ms 0 KB -

Subtask #5
0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 11612 KB Output is correct
2 Correct 1 ms 11612 KB Output is correct
3 Correct 1 ms 11612 KB Output is correct
4 Correct 1 ms 11612 KB Output is correct
5 Correct 2 ms 11612 KB Output is correct
6 Correct 1 ms 11612 KB Output is correct
7 Correct 1 ms 11612 KB Output is correct
8 Correct 2 ms 11608 KB Output is correct
9 Correct 1 ms 11612 KB Output is correct
10 Correct 1 ms 11612 KB Output is correct
11 Incorrect 1 ms 11612 KB impo2ssible is not a string of length exactly 7
12 Halted 0 ms 0 KB -