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Submission #444413

# Submission time Handle Problem Language Result Execution time Memory
444413 2021-07-14T04:29:06 Z limabeans The Xana coup (BOI21_xanadu) C++17
100 / 100
 123 ms 24692 KB 
#include <bits/stdc++.h>
using namespace std;

template<typename T>
void out(T x) { cout << x << endl; exit(0); }
#define watch(x) cout << (#x) << " is " << (x) << endl







const int maxn = 1e5 + 5;
const int inf = 1e7;


void setmin(int &x, int y) {
    x = min(x, y);
}

int n;
vector<int> g[maxn];
int a[maxn];

int dp[maxn][2][2];

//dp[at][value][flip/noflip] = min flips

void dfs(int at, int p) {
    for (int to: g[at]) {
	if (to == p) continue;
	dfs(to, at);
    }

    for (int flip: {0,1}) {
	dp[at][a[at]^flip][flip] = flip;
	dp[at][a[at]^flip^1][flip] = inf;
	
	for (int to: g[at]) {
	    if (to == p) continue;
	    vector<int> ndp = {inf, inf};
	    for (int tval: {0,1}) {
		if ((tval^flip) == 0) {
		    for (int tflip: {0,1}) {
			for (int aval: {0,1}) {
			    setmin(ndp[aval^tflip], dp[at][aval][flip]+dp[to][tval][tflip]);
			}
		    }
		}
	    }
	    
	    dp[at][0][flip] = ndp[0];
	    dp[at][1][flip] = ndp[1];
	}
    }
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0);  cout.tie(0);

    cin>>n;
    for (int i=0; i<n-1; i++) {
	int u,v; cin>>u>>v;
	--u; --v;
	g[u].push_back(v);
	g[v].push_back(u);
    }

    for (int i=0; i<n; i++) {
	cin>>a[i];
    }

    dfs(0, -1);

    // for (int v: {0,1}) {
    // 	for (int f: {0,1}) {
    // 	    cout<<v<<" "<<f<<": "<<dp[0][v][f]<<endl;
    // 	}
    // }

    int ans = inf;
    for (int flip: {0,1}) {
	ans = min(ans, dp[0][0][flip]);
    }

    if (ans == inf) out("impossible");
    out(ans);
    
    return 0;
}

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 2 ms 2668 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 2 ms 2636 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 2 ms 2668 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 2 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct
7 Correct 2 ms 2636 KB Output is correct
8 Correct 2 ms 2636 KB Output is correct
9 Correct 2 ms 2636 KB Output is correct
10 Correct 2 ms 2636 KB Output is correct
11 Correct 2 ms 2636 KB Output is correct
12 Correct 2 ms 2636 KB Output is correct
13 Correct 2 ms 2668 KB Output is correct
14 Correct 2 ms 2636 KB Output is correct
15 Correct 2 ms 2636 KB Output is correct
16 Correct 2 ms 2672 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 80 ms 24516 KB Output is correct
2 Correct 71 ms 24388 KB Output is correct
3 Correct 73 ms 24680 KB Output is correct

Subtask #4
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 71 ms 24516 KB Output is correct
2 Correct 83 ms 24304 KB Output is correct
3 Correct 71 ms 24692 KB Output is correct
4 Correct 68 ms 8388 KB Output is correct
5 Correct 67 ms 8848 KB Output is correct
6 Correct 70 ms 9028 KB Output is correct
7 Correct 2 ms 2636 KB Output is correct
8 Correct 22 ms 4892 KB Output is correct
9 Correct 81 ms 9092 KB Output is correct
10 Correct 77 ms 9172 KB Output is correct
11 Correct 82 ms 10136 KB Output is correct
12 Correct 72 ms 10436 KB Output is correct
13 Correct 64 ms 8632 KB Output is correct
14 Correct 76 ms 9052 KB Output is correct

Subtask #5
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 2 ms 2668 KB Output is correct
3 Correct 2 ms 2636 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 2 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct
7 Correct 2 ms 2636 KB Output is correct
8 Correct 2 ms 2636 KB Output is correct
9 Correct 2 ms 2636 KB Output is correct
10 Correct 2 ms 2636 KB Output is correct
11 Correct 2 ms 2636 KB Output is correct
12 Correct 2 ms 2636 KB Output is correct
13 Correct 2 ms 2668 KB Output is correct
14 Correct 2 ms 2636 KB Output is correct
15 Correct 2 ms 2636 KB Output is correct
16 Correct 2 ms 2672 KB Output is correct
17 Correct 80 ms 24516 KB Output is correct
18 Correct 71 ms 24388 KB Output is correct
19 Correct 73 ms 24680 KB Output is correct
20 Correct 71 ms 24516 KB Output is correct
21 Correct 83 ms 24304 KB Output is correct
22 Correct 71 ms 24692 KB Output is correct
23 Correct 68 ms 8388 KB Output is correct
24 Correct 67 ms 8848 KB Output is correct
25 Correct 70 ms 9028 KB Output is correct
26 Correct 2 ms 2636 KB Output is correct
27 Correct 22 ms 4892 KB Output is correct
28 Correct 81 ms 9092 KB Output is correct
29 Correct 77 ms 9172 KB Output is correct
30 Correct 82 ms 10136 KB Output is correct
31 Correct 72 ms 10436 KB Output is correct
32 Correct 64 ms 8632 KB Output is correct
33 Correct 76 ms 9052 KB Output is correct
34 Correct 2 ms 2636 KB Output is correct
35 Correct 2 ms 2636 KB Output is correct
36 Correct 2 ms 2636 KB Output is correct
37 Correct 2 ms 2636 KB Output is correct
38 Correct 2 ms 2636 KB Output is correct
39 Correct 2 ms 2636 KB Output is correct
40 Correct 2 ms 2636 KB Output is correct
41 Correct 2 ms 2636 KB Output is correct
42 Correct 2 ms 2636 KB Output is correct
43 Correct 2 ms 2636 KB Output is correct
44 Correct 2 ms 2672 KB Output is correct
45 Correct 82 ms 24552 KB Output is correct
46 Correct 76 ms 24360 KB Output is correct
47 Correct 97 ms 24692 KB Output is correct
48 Correct 61 ms 8344 KB Output is correct
49 Correct 72 ms 8900 KB Output is correct
50 Correct 77 ms 9036 KB Output is correct
51 Correct 2 ms 2636 KB Output is correct
52 Correct 25 ms 4832 KB Output is correct
53 Correct 75 ms 9052 KB Output is correct
54 Correct 78 ms 9220 KB Output is correct
55 Correct 74 ms 10180 KB Output is correct
56 Correct 83 ms 10476 KB Output is correct
57 Correct 84 ms 8564 KB Output is correct
58 Correct 86 ms 9044 KB Output is correct
59 Correct 21 ms 4764 KB Output is correct
60 Correct 80 ms 8588 KB Output is correct
61 Correct 123 ms 9060 KB Output is correct
62 Correct 76 ms 9224 KB Output is correct
63 Correct 73 ms 9180 KB Output is correct
64 Correct 88 ms 9220 KB Output is correct
65 Correct 61 ms 9540 KB Output is correct
66 Correct 62 ms 9592 KB Output is correct
67 Correct 62 ms 9432 KB Output is correct
68 Correct 59 ms 9484 KB Output is correct
69 Correct 55 ms 9404 KB Output is correct
70 Correct 52 ms 9588 KB Output is correct