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Submission #444016

# Submission time Handle Problem Language Result Execution time Memory
444016 2021-07-13T01:40:38 Z yungyao The Xana coup (BOI21_xanadu) C++17
50 / 100
 148 ms 19908 KB 
using namespace std;
#include <iostream>
#include <algorithm>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <utility>
#include <vector>
#include <memory.h>

typedef long long LL;
typedef pair<int,int> pii;
#define F first
#define S second
#define mkp make_pair
#define iter(x) x.begin(),x.end()
#define MEM(s,e) memset(s,e,sizeof(s))

const int maxn = 1e5+100,inf = 1e9;


int dp[maxn][2][2]; //index, t/f, on/off
bool status[maxn];

vector <int> adj[maxn];

void dfs(int x,int fr){
    int ldp[2][2][2],c=0;
    for (auto s:adj[x]) if (s != fr){
        dfs(s,x);
        for (int i=0;i<2;++i) for (int j=0;j<2;++j){
            ldp[c][i][j] = dp[s][i][j];
        }
        ++c;
    }
    if (!c){
        if (status[x]){
            dp[x][1][0] = 0;
            dp[x][0][1] = 1;
            dp[x][0][0] = inf;
            dp[x][1][1] = inf;
        }
        else{
            dp[x][0][0] = 0;
            dp[x][1][1] = 1;
            dp[x][1][0] = inf;
            dp[x][0][1] = inf;
        }
    }
    else if (c == 1){
        if (status[x]){
            dp[x][0][0] = ldp[0][0][1];
            dp[x][0][1] = ldp[0][1][0] + 1;
            dp[x][1][0] = ldp[0][0][0];
            dp[x][1][1] = ldp[0][1][1] + 1;
        }
        else{
            dp[x][0][0] = ldp[0][0][0];
            dp[x][0][1] = ldp[0][1][1] + 1;
            dp[x][1][0] = ldp[0][0][1];
            dp[x][1][1] = ldp[0][1][0] + 1;
        }
    }
    else{
        if (status[x]){
            dp[x][0][0] = min(inf,min(ldp[0][0][1] + ldp[1][0][0],ldp[0][0][0] + ldp[1][0][1]));
            dp[x][0][1] = min(inf,min(ldp[0][1][0] + ldp[1][1][0],ldp[0][1][1] + ldp[1][1][1]) + 1);
            dp[x][1][0] = min(inf,min(ldp[0][0][0] + ldp[1][0][0],ldp[0][0][1] + ldp[1][0][1]));
            dp[x][1][1] = min(inf,min(ldp[0][1][1] + ldp[1][1][0],ldp[0][1][0] + ldp[1][1][1]) + 1);
        }
        else{
            dp[x][0][0] = min(inf,min(ldp[0][0][0] + ldp[1][0][0],ldp[0][0][1] + ldp[1][0][1]));
            dp[x][0][1] = min(inf,min(ldp[0][1][1] + ldp[1][1][0],ldp[0][1][0] + ldp[1][1][1]) + 1);
            dp[x][1][0] = min(inf,min(ldp[0][0][1] + ldp[1][0][0],ldp[0][0][0] + ldp[1][0][1]));
            dp[x][1][1] = min(inf,min(ldp[0][1][0] + ldp[1][1][0],ldp[0][1][1] + ldp[1][1][1]) + 1);
        }
    }
}

int main(){
    int n;

    cin >> n;
    for (int _=n-1;_--;){
        int u,v;

        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    for (int i=1;i<=n;++i) cin >> status[i];
    for (int i=1;i<=n;++i) if (adj[i].size() == 1){
        dfs(i,0);
        int ans = min(dp[i][0][0],dp[i][0][1]);
        if (ans >= inf) cout << "impossible\n";
        else cout << ans << '\n';
        break;
    }
    return 0;
}

Subtask #1
0 / 5.0

# Verdict Execution time Memory Grader output
1 Runtime error 4 ms 5196 KB Execution killed with signal 6
2 Halted 0 ms 0 KB -

Subtask #2
0 / 15.0

# Verdict Execution time Memory Grader output
1 Runtime error 4 ms 5196 KB Execution killed with signal 6
2 Halted 0 ms 0 KB -

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 115 ms 19780 KB Output is correct
2 Correct 116 ms 19620 KB Output is correct
3 Correct 128 ms 19908 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 123 ms 19784 KB Output is correct
2 Correct 121 ms 19552 KB Output is correct
3 Correct 118 ms 19860 KB Output is correct
4 Correct 113 ms 6864 KB Output is correct
5 Correct 148 ms 8640 KB Output is correct
6 Correct 117 ms 8772 KB Output is correct
7 Correct 3 ms 2764 KB Output is correct
8 Correct 38 ms 4740 KB Output is correct
9 Correct 116 ms 8784 KB Output is correct
10 Correct 124 ms 8860 KB Output is correct
11 Correct 112 ms 9652 KB Output is correct
12 Correct 122 ms 9888 KB Output is correct
13 Correct 111 ms 8348 KB Output is correct
14 Correct 126 ms 8780 KB Output is correct

Subtask #5
0 / 30.0

# Verdict Execution time Memory Grader output
1 Runtime error 4 ms 5196 KB Execution killed with signal 6
2 Halted 0 ms 0 KB -