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Submission #745631

# Submission time Handle Problem Language Result Execution time Memory
745631 2023-05-20T16:46:36 Z MilosMilutinovic Beads and wires (APIO14_beads) C++14
100 / 100
 284 ms 34132 KB 
#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int N = 2e5 + 10;
const ll inf = 1e16;
ll dp[N][2][2]; // node, par edge, bad path
vector<pair<int, int>> g[N];
int n, w[N];
void setup() {
    for (int i = 1; i <= n; i++)
        for (int x = 0; x < 2; x++)
            for (int y = 0; y < 2; y++)
                dp[i][x][y] = -inf;
}
void solve(int x, int fa, int uw) {
    vector<int> ch;
    for (auto& p : g[x]) {
        int y = p.first;
        if (y == fa) continue;
        w[y] = p.second;
        solve(y, x, w[y]);
        ch.push_back(y);
    }
    if (ch.empty()) {
        dp[x][0][0] = 0;
        return;
    }

    // don't take x
    {
        vector<ll> cur(2, -inf);
        cur[0] = 0;
        for (int y : ch) {
            vector<ll> ndp(2, -inf);
            ndp[0] = max(ndp[0], cur[0] + dp[y][0][0]);
            ndp[0] = max(ndp[0], cur[0] + dp[y][1][0]);

            ndp[1] = max(ndp[1], cur[0] + dp[y][0][1]);
            ndp[1] = max(ndp[1], cur[0] + dp[y][1][1]);

            ndp[1] = max(ndp[1], cur[1] + dp[y][0][0]);
            ndp[1] = max(ndp[1], cur[1] + dp[y][1][0]);
            swap(cur, ndp);
        }
        dp[x][0][0] = max(dp[x][0][0], cur[0]);
        dp[x][0][1] = max(dp[x][0][1], cur[1]);
    }

    // take x, from 2 down
    {
        vector<vector<ll>> cur(3, vector<ll>(2, -inf));
        cur[0][0] = 0;
        for (int y : ch) {
            vector<vector<ll>> ndp(3, vector<ll>(2, -inf));

            // don't take y
            for (int i = 0; i < 3; i++) {
                for (int j = 0; j < 2; j++) {
                    ndp[i][j] = max(ndp[i][j], cur[i][j] + dp[y][0][0]);
                    ndp[i][j] = max(ndp[i][j], cur[i][j] + dp[y][1][0]);
                }
            }

            // take y
            for (int i = 0; i < 2; i++) {
                for (int j = 0; j < 2; j++) {
                    for (int o = 0; o < 2; o++) {
                        if (j + o == 2) continue;
                        ndp[i + 1][j + o] = max(ndp[i + 1][j + o], cur[i][j] + dp[y][0][o] + w[y]);
                    }
                }
            }

            swap(cur, ndp);
        }
        dp[x][0][1] = max({dp[x][0][1], cur[2][0], cur[2][1]});
    }

    // take x, from 1 down 1 up
    {
        vector<vector<ll>> cur(2, vector<ll>(2, -inf));
        cur[0][0] = 0;
        for (int y : ch) {
            vector<vector<ll>> ndp(2, vector<ll>(2, -inf));

            // don't take y
            for (int i = 0; i < 2; i++) {
                for (int j = 0; j < 2; j++) {
                    ndp[i][j] = max(ndp[i][j], cur[i][j] + dp[y][0][0]);
                    ndp[i][j] = max(ndp[i][j], cur[i][j] + dp[y][1][0]);
                }
            }

            // take y
            for (int i = 0; i < 1; i++) {
                for (int j = 0; j < 2; j++) {
                    for (int o = 0; o < 2; o++) {
                        if (j + o == 2) continue;
                        ndp[i + 1][j + o] = max(ndp[i + 1][j + o], cur[i][j] + dp[y][0][o] + w[y]);
                    }
                }
            }

            swap(cur, ndp);
        }
        dp[x][1][0] = max(dp[x][1][0], cur[1][0] + uw);
        dp[x][1][1] = max(dp[x][1][1], cur[1][1] + uw);
    }

}
int main() {
    scanf("%d", &n);
    for (int i = 1; i < n; i++) {
        int a, b, c;
        scanf("%d%d%d", &a, &b, &c);
        g[a].push_back({b, c});
        g[b].push_back({a, c});
    }
    setup();
    solve(1, 1, -inf / 10);
    printf("%lld\n", max(dp[1][0][0], dp[1][0][1]));
    return 0;
}

/*
5
1 2 10
1 3 40
1 4 15
1 5 20

60

10
4 10 2
1 2 21
1 3 13
6 7 1
7 9 5
2 4 3
2 5 8
1 6 55
6 8 34

140


6
1 3 100
2 3 100
3 4 1
4 5 100
4 6 100

7
1 2 100
1 3 100
2 4 100
2 5 100
3 6 100
3 7 100
*/

Compilation message

beads.cpp: In function 'int main()':
beads.cpp:120:22: warning: overflow in conversion from 'long long int' to 'int' changes value from '-1000000000000000' to '1530494976' [-Woverflow]
  120 |     solve(1, 1, -inf / 10);
      |                 ~~~~~^~~~
beads.cpp:112:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  112 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
beads.cpp:115:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  115 |         scanf("%d%d%d", &a, &b, &c);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~

Subtask #1
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 2 ms 4948 KB Output is correct
4 Correct 2 ms 4948 KB Output is correct
5 Correct 3 ms 4900 KB Output is correct
6 Correct 3 ms 4948 KB Output is correct
7 Correct 3 ms 4948 KB Output is correct
8 Correct 3 ms 4948 KB Output is correct
9 Correct 3 ms 4948 KB Output is correct
10 Correct 3 ms 5016 KB Output is correct
11 Correct 3 ms 5016 KB Output is correct
12 Correct 3 ms 5016 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 2 ms 4948 KB Output is correct
4 Correct 2 ms 4948 KB Output is correct
5 Correct 3 ms 4900 KB Output is correct
6 Correct 3 ms 4948 KB Output is correct
7 Correct 3 ms 4948 KB Output is correct
8 Correct 3 ms 4948 KB Output is correct
9 Correct 3 ms 4948 KB Output is correct
10 Correct 3 ms 5016 KB Output is correct
11 Correct 3 ms 5016 KB Output is correct
12 Correct 3 ms 5016 KB Output is correct
13 Correct 4 ms 4948 KB Output is correct
14 Correct 3 ms 5076 KB Output is correct
15 Correct 3 ms 5020 KB Output is correct
16 Correct 3 ms 4948 KB Output is correct
17 Correct 3 ms 4948 KB Output is correct
18 Correct 3 ms 4948 KB Output is correct
19 Correct 3 ms 4948 KB Output is correct
20 Correct 3 ms 5012 KB Output is correct
21 Correct 3 ms 4948 KB Output is correct
22 Correct 3 ms 5012 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 2 ms 4948 KB Output is correct
4 Correct 2 ms 4948 KB Output is correct
5 Correct 3 ms 4900 KB Output is correct
6 Correct 3 ms 4948 KB Output is correct
7 Correct 3 ms 4948 KB Output is correct
8 Correct 3 ms 4948 KB Output is correct
9 Correct 3 ms 4948 KB Output is correct
10 Correct 3 ms 5016 KB Output is correct
11 Correct 3 ms 5016 KB Output is correct
12 Correct 3 ms 5016 KB Output is correct
13 Correct 4 ms 4948 KB Output is correct
14 Correct 3 ms 5076 KB Output is correct
15 Correct 3 ms 5020 KB Output is correct
16 Correct 3 ms 4948 KB Output is correct
17 Correct 3 ms 4948 KB Output is correct
18 Correct 3 ms 4948 KB Output is correct
19 Correct 3 ms 4948 KB Output is correct
20 Correct 3 ms 5012 KB Output is correct
21 Correct 3 ms 4948 KB Output is correct
22 Correct 3 ms 5012 KB Output is correct
23 Correct 8 ms 5332 KB Output is correct
24 Correct 8 ms 5416 KB Output is correct
25 Correct 7 ms 5332 KB Output is correct
26 Correct 11 ms 5840 KB Output is correct
27 Correct 11 ms 5844 KB Output is correct
28 Correct 9 ms 5972 KB Output is correct
29 Correct 10 ms 5952 KB Output is correct
30 Correct 10 ms 5956 KB Output is correct
31 Correct 12 ms 6764 KB Output is correct

Subtask #4
43.0 / 43.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 2 ms 4948 KB Output is correct
4 Correct 2 ms 4948 KB Output is correct
5 Correct 3 ms 4900 KB Output is correct
6 Correct 3 ms 4948 KB Output is correct
7 Correct 3 ms 4948 KB Output is correct
8 Correct 3 ms 4948 KB Output is correct
9 Correct 3 ms 4948 KB Output is correct
10 Correct 3 ms 5016 KB Output is correct
11 Correct 3 ms 5016 KB Output is correct
12 Correct 3 ms 5016 KB Output is correct
13 Correct 4 ms 4948 KB Output is correct
14 Correct 3 ms 5076 KB Output is correct
15 Correct 3 ms 5020 KB Output is correct
16 Correct 3 ms 4948 KB Output is correct
17 Correct 3 ms 4948 KB Output is correct
18 Correct 3 ms 4948 KB Output is correct
19 Correct 3 ms 4948 KB Output is correct
20 Correct 3 ms 5012 KB Output is correct
21 Correct 3 ms 4948 KB Output is correct
22 Correct 3 ms 5012 KB Output is correct
23 Correct 8 ms 5332 KB Output is correct
24 Correct 8 ms 5416 KB Output is correct
25 Correct 7 ms 5332 KB Output is correct
26 Correct 11 ms 5840 KB Output is correct
27 Correct 11 ms 5844 KB Output is correct
28 Correct 9 ms 5972 KB Output is correct
29 Correct 10 ms 5952 KB Output is correct
30 Correct 10 ms 5956 KB Output is correct
31 Correct 12 ms 6764 KB Output is correct
32 Correct 52 ms 9396 KB Output is correct
33 Correct 51 ms 9396 KB Output is correct
34 Correct 51 ms 9396 KB Output is correct
35 Correct 254 ms 23060 KB Output is correct
36 Correct 284 ms 23120 KB Output is correct
37 Correct 271 ms 23028 KB Output is correct
38 Correct 174 ms 25176 KB Output is correct
39 Correct 164 ms 24440 KB Output is correct
40 Correct 213 ms 24344 KB Output is correct
41 Correct 234 ms 34132 KB Output is correct