Submission #1036147

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
1036147	2024-07-27T04:14:16 Z	sleepntsheep	Islands (IOI08_islands)	C	48 / 100	199 ms	112468 KB

islands

#include <stdio.h>

#define NN 1000001
#define MM 2000002

long long max(long long i, long long j) {return i > j ? i : j;} 

int n, ww[MM], to[MM], lnk[MM], head[NN], col[NN];

void link(int u, int v, int w) {
    static int ii = 0;
    int i = ++ii;
    to[i] = v;
    ww[i] = w;
    lnk[i] = head[u];
    head[u] = i;
}

int cycle_head, cycle_tail;
int cyc[NN], co, par[NN], incyc[NN];
long long tentacle[NN], aa[NN];

int dfs(int u, int p) {
    par[u] = p;
    col[u] = 1;

    for (int j = head[u]; j; j = lnk[j]) {
        int v = to[j];
        if (v == p) continue;
        if (col[v]) {
            cycle_head = u;
            cycle_tail = v;

            co = 0;
            int cur = u;
            for (; cur != v && cur != -1; cur = par[cur])
                incyc[cyc[co++] = cur] = 1;
            incyc[cyc[co++] = v] = 1;

            return 1;
        }
        if (dfs(v, u))
            return 1;
    }
    return 0;
}

void dfs2(int u, int p) {
    col[u] = 1;
    for (int j = head[u]; j; j = lnk[j]) {
        int v = to[j];
        if (v == p || incyc[v]) continue;
        dfs2(v, u);
        if (tentacle[v] + ww[j] > tentacle[u])
            tentacle[u] = tentacle[v] + ww[j];
    }
}

long long answer = 0;

int main() {
    scanf("%d", &n);
    for (int i = 1, j, k; i <= n; ++i)
        scanf("%d%d", &j, &k), link(i, j, k), link(j, i, k);

    for (int ii = 1; ii <= n; ++ii) {
        if (col[ii]) continue;

        dfs(ii, -1);

        long long op0 = -1e18, op1 = -1e18, here = 0;

        if (co == 2) {
            for (int j = head[cycle_head]; j; j = lnk[j])
                if (cycle_tail == to[j])
                    here = max(here, ww[j]);
            answer += here;
            continue;
        }

        long long cycle_w = 0;
        for (int i = 0; i < co; ++i) {
            for (int j = head[cyc[i]]; j; j = lnk[j])
                if (incyc[to[j]]) cycle_w += ww[j];
            dfs2(cyc[i], -1);
        }
        cycle_w /= 2;

        for (int i = 0; i < co; ++i) {
            here = max(here, tentacle[cyc[i]] + max(aa[i] + op0, -aa[i] + op1));

            op0 = max(tentacle[cyc[i]] - aa[i], op0);
            op1 = max(tentacle[cyc[i]] + cycle_w + aa[i], op1);

            if (i + 1 < co)
                for (int j = head[cyc[i]]; j; j = lnk[j])
                    if (to[j] == cyc[i + 1]) {
                        aa[i + 1] = aa[i] + ww[j];
                        break;
                    }
        }

        answer += here;
    }
    printf("%lld\n", answer);
}

Compilation message

islands.c: In function 'main':
islands.c:62:5: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   62 |     scanf("%d", &n);
      |     ^~~~~~~~~~~~~~~
islands.c:64:9: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   64 |         scanf("%d%d", &j, &k), link(i, j, k), link(j, i, k);
      |         ^~~~~~~~~~~~~~~~~~~~~

Subtask #1
15.0 / 33.0

#	Verdict	Memory	Grader output
1	Correct	344 KB	Output is correct
2	Incorrect	344 KB	Output isn't correct
3	Correct	348 KB	Output is correct
4	Incorrect	348 KB	Output isn't correct
5	Correct	348 KB	Output is correct
6	Incorrect	348 KB	Output isn't correct
7	Incorrect	348 KB	Output isn't correct
8	Correct	348 KB	Output is correct
9	Incorrect	348 KB	Output isn't correct
10	Incorrect	348 KB	Output isn't correct
11	Correct	348 KB	Output is correct

Subtask #2
3.0 / 3.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	0 ms	348 KB	Output is correct
2	Correct	0 ms	348 KB	Output is correct

Subtask #3
0 / 4.0

#	Verdict	Execution time	Memory	Grader output
1	Incorrect	1 ms	348 KB	Output isn't correct
2	Halted	0 ms	0 KB	-

Subtask #4
0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	3 ms	1116 KB	Output is correct
2	Correct	8 ms	3420 KB	Output is correct
3	Incorrect	5 ms	1628 KB	Output isn't correct
4	Halted	0 ms	0 KB	-

Subtask #5
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	11 ms	4188 KB	Output is correct
2	Correct	16 ms	6236 KB	Output is correct

Subtask #6
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	35 ms	11348 KB	Output is correct
2	Correct	36 ms	15188 KB	Output is correct
3	Correct	46 ms	23376 KB	Output is correct

Subtask #7
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	65 ms	19540 KB	Output is correct
2	Correct	89 ms	44112 KB	Output is correct
3	Correct	96 ms	48784 KB	Output is correct
4	Correct	120 ms	67900 KB	Output is correct

Subtask #8
0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Incorrect	147 ms	32900 KB	Output isn't correct
2	Halted	0 ms	0 KB	-

Subtask #9
0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Incorrect	199 ms	112468 KB	Output isn't correct
2	Halted	0 ms	0 KB	-