oj.uz

Submission #953940

# Submission time Handle Problem Language Result Execution time Memory
953940 2024-03-27T00:10:25 Z sofiefu The Xana coup (BOI21_xanadu) C++14
100 / 100
 107 ms 18364 KB 
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define vo vector
#define pb push_back
#define se second
#define fi first
#define all(v) v.begin(), v.end()
typedef vector<int> vi;
typedef pair<int, int> pii;
#define umap unordered_map
#define uset unordered_set

#define rep(i, a, b) for(int i=(a); i<b; i++)
#define pr1(x) cerr << #x << '=' << x << ' ';
//for google contests
#define repd(i, a, b) for(int i=(b-1); i >= a; i--)
void _pr(signed x) {cerr << x;}
void _pr(long long x) {cerr << x;}
void _pr(unsigned long long x) {cerr << x;}
void _pr(double x) {cerr << x;}
void _pr(char x) {cerr << '\'' << x << '\'';}
void _pr(const char* x) {cerr << x;}
void _pr(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V> void _pr(const pair<T, V> &x);
template<typename T, typename V> void _pr(const pair<T, V> &x) {cerr << "\e[95m" << "[ "; _pr(x.first); cerr << ", "; _pr(x.second); cerr << "\e[95m" << ']';}
template<typename T> void _pr(const T &x) {int F=0; cerr << '{'; for(auto &i: x) cerr << (F++ ? ", " : ""), _pr(i); cerr << "\e[91m" << '}';}
template <typename T, typename... V> void _pr(T t, V... v) {_pr(t); if(sizeof...(v)) cerr << ", "; _pr(v...);}
#define pr(x...) cerr << "\e[91m" << __func__ << ':' << __LINE__ << " [" << #x << "] = ["; _pr(x); cerr << "\e[91m" << ']' << "\033[0m"  << endl;

//go for outline with ;, then details
int const inf = 1e9, mxn = 1e5+4;
int n, ans=inf;
vo<vi> adj(mxn);
vi col, ini, off;

void press(int at){
    col[at] = 1-col[at];
    for(auto x: adj[at]){
        col[x] = 1-col[x];
    }
}

void sol1(){
    rep(mask, 0, (1<<n)){
        int ct = 0;
        col = ini;
        rep(i, 0, n){
            if(mask & (1<<i)){
                press(i);
                ct++;
            }
        }

        if(off == col) ans = min(ans, ct);
    }
}

void sol3(){
    int ct = 0;
    rep(i, 1, n){
        if(col[i-1]){
            col[i-1] = 0; col[i] ^= 1;
            if(i<n-1) col[i+1] ^= 1;
            ct++;
        }

        if(i==n-1 && !col[i]) ans = min(ans, ct);
    }

    ct = 0;
    col = ini; col[0] ^= 1; col[1] ^= 1;
    rep(i, 1, n){
        if(col[i-1]){
            col[i-1] = 0; col[i] ^= 1;
            if(i<n-1) col[i+1] ^= 1;
            ct++;
        }
    
        if(i==n-1 && !col[i]) ans = min(ans, ct);
    }
}

vi dfs(int at, int p){ //press and my color after press
    vi ret = {inf, inf, inf, inf};
    vo<vi> kids;

    for(auto x: adj[at]){
        if(x==p) continue;
        vi tmp = dfs(x, at);
        kids.pb(tmp);
    }
    if(kids.size() == 0){
        if(ini[at]) ret = {1, inf, inf, 0};
        else ret = {inf, 1, 0, inf};
    }
    else if(kids.size() == 1){ 
        if(ini[at]){
            ret = {min(inf, kids[0][3]+1), min(inf, kids[0][1]+1), kids[0][0], kids[0][2]};
        }
        else{
            ret = {min(inf, kids[0][1]+1), min(inf, kids[0][3]+1), kids[0][2], kids[0][0]};
        }
    }
    else{
        vi a = kids[0], b = kids[1];
        //press
        for(int i: {1, 3}){
            for(int u: {1, 3}){
                if(a[i]==inf || b[u] == inf) continue;
                int ind = ((ini[at]^1) + (i==1) + (u==1))%2;
                ret[ind] = min(ret[ind], a[i] + b[u] + 1);
                
            }
        }
        //dont press
        for(int i: {0, 2}){
            for(int u: {0, 2}){
                if(a[i]==inf && b[u] == inf) continue;
                int ind = (ini[at] + (i==0) + (u==0))%2 + 2;
                ret[ind] = min(ret[ind], a[i] + b[u]);
            }
        }
    }

    return ret;
}

vi full(int at, int p){
    vi ret = {inf, inf, inf, inf};
    vo<vi> kids;

    for(auto x: adj[at]){
        if(x==p) continue;
        vi tmp = full(x, at);
        kids.pb(tmp);
    }
    if(kids.size() == 0){
        if(ini[at]) ret = {1, inf, inf, 0};
        else ret = {inf, 1, 0, inf};
    }
    else{
        //find cheapest for all children and swap one to get reverse color
        //press so all kids white
        int sum = 1, posi = 1, ind = 0, cheap = inf;
        for(auto v: kids){
            if(v[3] > v[1]) {
                sum += v[1];
                ind++;
                if(v[3]!=inf) cheap = min(cheap, v[3]-v[1]);
            }
            else{
                if(v[3] == v[1] && v[1] == inf) {posi = 0; break;}
                sum += v[3];
                if(v[1] != inf) cheap = min(cheap, v[1]-v[3]);
            }
        }
        if(posi){
            ind = ((ini[at]^1) + ind)%2;
            ret[ind] = sum;
            if(cheap != inf) ret[ind^1] = sum + cheap;
        }

        //dont press
        sum = 0, posi = 1, ind = 0, cheap = inf;
        for(auto v: kids){
            if(v[2] > v[0]) {
                sum += v[0];
                ind++;
                if(v[2] != inf) cheap = min(cheap, v[2]-v[0]);
            }
            else{
                if(v[2] == v[0] && v[0] == inf) {posi = 0; break;}
                sum += v[2];
                if(v[0] != inf) cheap = min(cheap, v[0]-v[2]);
            }
        }
        if(posi){
            ind = (ini[at] + ind)%2;
            ret[ind+2] = sum;
            if(cheap != inf) ret[(ind^1) + 2] = sum + cheap;
        }
    }

    return ret; 
}

signed main(){
    cin.tie(0)->sync_with_stdio(0);
    cin>>n; col.resize(n), ini.resize(n), off.assign(n, 0); 
    vi indeg(n, 0);
    int linegraph = 1;
    rep(i, 0, n-1){
        int a, b; cin>>a>>b; a--, --b;
        adj[a].pb(b), adj[b].pb(a); indeg[a]++, indeg[b]++;
        if(abs(a-b) > 1) linegraph = 0;
    }

    rep(i, 0, n) {
        cin>>col[i]; ini[i] = col[i];
    }

    if(n<=20){
        sol1();
    }
    // else if(n<=40) ;//press centroid and then do bitmask on each subtree
    else if(linegraph){
        sol3();
    }
    else if(0){
        //binary tree
        rep(i, 0, n){
            if(indeg[i] == 1){
                vi tmp = dfs(i, i);
                ans = min(tmp[0], tmp[2]);
                break;
            }
        }
    }
    else{
        vi tmp = full(0, 0);
        ans = min(tmp[0], tmp[2]);
    }
    

    (ans==inf) ? cout << "impossible" : cout << ans;
}

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 2648 KB Output is correct
2 Correct 3 ms 2652 KB Output is correct
3 Correct 104 ms 2616 KB Output is correct
4 Correct 103 ms 2648 KB Output is correct
5 Correct 103 ms 2652 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 2648 KB Output is correct
2 Correct 3 ms 2652 KB Output is correct
3 Correct 104 ms 2616 KB Output is correct
4 Correct 103 ms 2648 KB Output is correct
5 Correct 103 ms 2652 KB Output is correct
6 Correct 13 ms 2904 KB Output is correct
7 Correct 2 ms 2652 KB Output is correct
8 Correct 105 ms 2652 KB Output is correct
9 Correct 104 ms 2648 KB Output is correct
10 Correct 103 ms 2648 KB Output is correct
11 Correct 2 ms 2652 KB Output is correct
12 Correct 1 ms 2652 KB Output is correct
13 Correct 2 ms 2652 KB Output is correct
14 Correct 1 ms 2816 KB Output is correct
15 Correct 1 ms 2652 KB Output is correct
16 Correct 1 ms 2652 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 31 ms 10316 KB Output is correct
2 Correct 33 ms 10060 KB Output is correct
3 Correct 29 ms 10416 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 29 ms 10352 KB Output is correct
2 Correct 38 ms 10064 KB Output is correct
3 Correct 29 ms 10324 KB Output is correct
4 Correct 40 ms 10324 KB Output is correct
5 Correct 43 ms 11088 KB Output is correct
6 Correct 44 ms 11244 KB Output is correct
7 Correct 1 ms 2648 KB Output is correct
8 Correct 15 ms 5720 KB Output is correct
9 Correct 66 ms 10836 KB Output is correct
10 Correct 49 ms 11088 KB Output is correct
11 Correct 45 ms 12880 KB Output is correct
12 Correct 46 ms 13396 KB Output is correct
13 Correct 41 ms 10840 KB Output is correct
14 Correct 59 ms 11600 KB Output is correct

Subtask #5
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 2648 KB Output is correct
2 Correct 3 ms 2652 KB Output is correct
3 Correct 104 ms 2616 KB Output is correct
4 Correct 103 ms 2648 KB Output is correct
5 Correct 103 ms 2652 KB Output is correct
6 Correct 13 ms 2904 KB Output is correct
7 Correct 2 ms 2652 KB Output is correct
8 Correct 105 ms 2652 KB Output is correct
9 Correct 104 ms 2648 KB Output is correct
10 Correct 103 ms 2648 KB Output is correct
11 Correct 2 ms 2652 KB Output is correct
12 Correct 1 ms 2652 KB Output is correct
13 Correct 2 ms 2652 KB Output is correct
14 Correct 1 ms 2816 KB Output is correct
15 Correct 1 ms 2652 KB Output is correct
16 Correct 1 ms 2652 KB Output is correct
17 Correct 31 ms 10316 KB Output is correct
18 Correct 33 ms 10060 KB Output is correct
19 Correct 29 ms 10416 KB Output is correct
20 Correct 29 ms 10352 KB Output is correct
21 Correct 38 ms 10064 KB Output is correct
22 Correct 29 ms 10324 KB Output is correct
23 Correct 40 ms 10324 KB Output is correct
24 Correct 43 ms 11088 KB Output is correct
25 Correct 44 ms 11244 KB Output is correct
26 Correct 1 ms 2648 KB Output is correct
27 Correct 15 ms 5720 KB Output is correct
28 Correct 66 ms 10836 KB Output is correct
29 Correct 49 ms 11088 KB Output is correct
30 Correct 45 ms 12880 KB Output is correct
31 Correct 46 ms 13396 KB Output is correct
32 Correct 41 ms 10840 KB Output is correct
33 Correct 59 ms 11600 KB Output is correct
34 Correct 16 ms 2652 KB Output is correct
35 Correct 3 ms 2652 KB Output is correct
36 Correct 107 ms 2652 KB Output is correct
37 Correct 104 ms 2652 KB Output is correct
38 Correct 103 ms 2648 KB Output is correct
39 Correct 1 ms 2652 KB Output is correct
40 Correct 1 ms 2652 KB Output is correct
41 Correct 1 ms 2652 KB Output is correct
42 Correct 1 ms 2652 KB Output is correct
43 Correct 1 ms 2652 KB Output is correct
44 Correct 1 ms 2652 KB Output is correct
45 Correct 30 ms 10152 KB Output is correct
46 Correct 33 ms 10128 KB Output is correct
47 Correct 30 ms 10332 KB Output is correct
48 Correct 39 ms 10236 KB Output is correct
49 Correct 44 ms 11092 KB Output is correct
50 Correct 48 ms 11100 KB Output is correct
51 Correct 1 ms 2904 KB Output is correct
52 Correct 15 ms 5720 KB Output is correct
53 Correct 47 ms 11052 KB Output is correct
54 Correct 45 ms 11088 KB Output is correct
55 Correct 58 ms 12880 KB Output is correct
56 Correct 54 ms 13380 KB Output is correct
57 Correct 41 ms 10832 KB Output is correct
58 Correct 44 ms 11612 KB Output is correct
59 Correct 16 ms 5468 KB Output is correct
60 Correct 44 ms 10240 KB Output is correct
61 Correct 47 ms 10832 KB Output is correct
62 Correct 44 ms 11100 KB Output is correct
63 Correct 59 ms 11356 KB Output is correct
64 Correct 47 ms 11088 KB Output is correct
65 Correct 49 ms 11608 KB Output is correct
66 Correct 53 ms 11352 KB Output is correct
67 Correct 40 ms 18116 KB Output is correct
68 Correct 42 ms 18112 KB Output is correct
69 Correct 40 ms 18364 KB Output is correct
70 Correct 47 ms 18224 KB Output is correct