oj.uz

Submission #1058644

# Submission time Handle Problem Language Result Execution time Memory
1058644 2024-08-14T11:43:08 Z otarius Alternating Current (BOI18_alternating) C++17
0 / 100
 81 ms 15056 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].cl);
            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 << "impossible";
    } 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 2 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 1 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 1 ms 11612 KB Output is correct
9 Correct 1 ms 11612 KB Output is correct
10 Correct 1 ms 11612 KB Output is correct
11 Correct 1 ms 11612 KB Output is correct
12 Correct 1 ms 11612 KB Output is correct
13 Correct 1 ms 11612 KB Output is correct
14 Correct 1 ms 11612 KB Output is correct
15 Correct 1 ms 11612 KB Output is correct
16 Correct 1 ms 11612 KB Output is correct
17 Correct 1 ms 11612 KB Output is correct
18 Correct 1 ms 11612 KB Output is correct
19 Correct 1 ms 11612 KB Output is correct
20 Correct 1 ms 11612 KB Output is correct
21 Correct 1 ms 11612 KB Output is correct
22 Correct 2 ms 11612 KB Output is correct
23 Correct 1 ms 11612 KB Output is correct
24 Correct 1 ms 11612 KB Output is correct
25 Correct 2 ms 11612 KB Output is correct
26 Correct 2 ms 11612 KB Output is correct
27 Correct 2 ms 11612 KB Output is correct
28 Correct 1 ms 11612 KB Output is correct
29 Correct 1 ms 11612 KB Output is correct
30 Correct 1 ms 11612 KB Output is correct
31 Correct 1 ms 11612 KB Output is correct
32 Correct 1 ms 11612 KB Output is correct
33 Correct 1 ms 11612 KB Output is correct
34 Correct 1 ms 11612 KB Output is correct
35 Correct 1 ms 11612 KB Output is correct
36 Correct 2 ms 11612 KB Output is correct
37 Incorrect 1 ms 11612 KB 'impossible' claimed, but there is a solution
38 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 2 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 1 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 1 ms 11612 KB Output is correct
9 Correct 1 ms 11612 KB Output is correct
10 Correct 1 ms 11612 KB Output is correct
11 Correct 1 ms 11612 KB Output is correct
12 Correct 1 ms 11612 KB Output is correct
13 Correct 1 ms 11612 KB Output is correct
14 Correct 1 ms 11612 KB Output is correct
15 Correct 1 ms 11612 KB Output is correct
16 Correct 1 ms 11612 KB Output is correct
17 Correct 1 ms 11612 KB Output is correct
18 Correct 1 ms 11612 KB Output is correct
19 Correct 1 ms 11612 KB Output is correct
20 Correct 1 ms 11612 KB Output is correct
21 Correct 1 ms 11612 KB Output is correct
22 Correct 2 ms 11612 KB Output is correct
23 Correct 1 ms 11612 KB Output is correct
24 Correct 1 ms 11612 KB Output is correct
25 Correct 2 ms 11612 KB Output is correct
26 Correct 2 ms 11612 KB Output is correct
27 Correct 2 ms 11612 KB Output is correct
28 Correct 1 ms 11612 KB Output is correct
29 Correct 1 ms 11612 KB Output is correct
30 Correct 1 ms 11612 KB Output is correct
31 Correct 1 ms 11612 KB Output is correct
32 Correct 1 ms 11612 KB Output is correct
33 Correct 1 ms 11612 KB Output is correct
34 Correct 1 ms 11612 KB Output is correct
35 Correct 1 ms 11612 KB Output is correct
36 Correct 2 ms 11612 KB Output is correct
37 Incorrect 1 ms 11612 KB 'impossible' claimed, but there is a solution
38 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 2 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 1 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 1 ms 11612 KB Output is correct
9 Correct 1 ms 11612 KB Output is correct
10 Correct 1 ms 11612 KB Output is correct
11 Correct 1 ms 11612 KB Output is correct
12 Correct 1 ms 11612 KB Output is correct
13 Correct 1 ms 11612 KB Output is correct
14 Correct 1 ms 11612 KB Output is correct
15 Correct 1 ms 11612 KB Output is correct
16 Correct 1 ms 11612 KB Output is correct
17 Correct 1 ms 11612 KB Output is correct
18 Correct 1 ms 11612 KB Output is correct
19 Correct 1 ms 11612 KB Output is correct
20 Correct 1 ms 11612 KB Output is correct
21 Correct 1 ms 11612 KB Output is correct
22 Correct 2 ms 11612 KB Output is correct
23 Correct 1 ms 11612 KB Output is correct
24 Correct 1 ms 11612 KB Output is correct
25 Correct 2 ms 11612 KB Output is correct
26 Correct 2 ms 11612 KB Output is correct
27 Correct 2 ms 11612 KB Output is correct
28 Correct 1 ms 11612 KB Output is correct
29 Correct 1 ms 11612 KB Output is correct
30 Correct 1 ms 11612 KB Output is correct
31 Correct 1 ms 11612 KB Output is correct
32 Correct 1 ms 11612 KB Output is correct
33 Correct 1 ms 11612 KB Output is correct
34 Correct 1 ms 11612 KB Output is correct
35 Correct 1 ms 11612 KB Output is correct
36 Correct 2 ms 11612 KB Output is correct
37 Incorrect 1 ms 11612 KB 'impossible' claimed, but there is a solution
38 Halted 0 ms 0 KB -

Subtask #4
0 / 19.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 12348 KB Output is correct
2 Correct 2 ms 11608 KB Output is correct
3 Correct 45 ms 12124 KB Output is correct
4 Correct 22 ms 12120 KB Output is correct
5 Correct 53 ms 14548 KB Output is correct
6 Correct 81 ms 13904 KB Output is correct
7 Correct 53 ms 12976 KB Output is correct
8 Correct 3 ms 11612 KB Output is correct
9 Correct 2 ms 11612 KB Output is correct
10 Correct 53 ms 14792 KB Output is correct
11 Correct 41 ms 13648 KB Output is correct
12 Correct 42 ms 12256 KB Output is correct
13 Correct 2 ms 11608 KB Output is correct
14 Correct 2 ms 11612 KB Output is correct
15 Correct 48 ms 12428 KB Output is correct
16 Correct 45 ms 15056 KB Output is correct
17 Correct 65 ms 12360 KB Output is correct
18 Incorrect 57 ms 14684 KB 'impossible' claimed, but there is a solution
19 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 2 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 1 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 1 ms 11612 KB Output is correct
9 Correct 1 ms 11612 KB Output is correct
10 Correct 1 ms 11612 KB Output is correct
11 Correct 1 ms 11612 KB Output is correct
12 Correct 1 ms 11612 KB Output is correct
13 Correct 1 ms 11612 KB Output is correct
14 Correct 1 ms 11612 KB Output is correct
15 Correct 1 ms 11612 KB Output is correct
16 Correct 1 ms 11612 KB Output is correct
17 Correct 1 ms 11612 KB Output is correct
18 Correct 1 ms 11612 KB Output is correct
19 Correct 1 ms 11612 KB Output is correct
20 Correct 1 ms 11612 KB Output is correct
21 Correct 1 ms 11612 KB Output is correct
22 Correct 2 ms 11612 KB Output is correct
23 Correct 1 ms 11612 KB Output is correct
24 Correct 1 ms 11612 KB Output is correct
25 Correct 2 ms 11612 KB Output is correct
26 Correct 2 ms 11612 KB Output is correct
27 Correct 2 ms 11612 KB Output is correct
28 Correct 1 ms 11612 KB Output is correct
29 Correct 1 ms 11612 KB Output is correct
30 Correct 1 ms 11612 KB Output is correct
31 Correct 1 ms 11612 KB Output is correct
32 Correct 1 ms 11612 KB Output is correct
33 Correct 1 ms 11612 KB Output is correct
34 Correct 1 ms 11612 KB Output is correct
35 Correct 1 ms 11612 KB Output is correct
36 Correct 2 ms 11612 KB Output is correct
37 Incorrect 1 ms 11612 KB 'impossible' claimed, but there is a solution
38 Halted 0 ms 0 KB -