Submission #56474

#	Time	Username	Problem	Language	Result	Execution time	Memory
56474		aquablitz11	Teleporters (IOI08_teleporters)	C++14	85 / 100	885 ms	66560 KiB

teleporters

#include <bits/stdc++.h>
using namespace std;

const int N = 1000010;

int n, m;
int A[N], B[N], pos[2*N], coord[2*N], nxt[2*N];
bool vis[2*N];

int main()
{
    scanf("%d%d", &n, &m);
    for (int i = 0; i < n; ++i) {
        scanf("%d%d", &A[i], &B[i]);
        coord[2*i+1] = A[i];
        coord[2*i+2] = B[i];
    }
    sort(coord, coord+2*n+1);
    for (int i = 0; i < 2*n+1; ++i)
        pos[coord[i]] = i;
    for (int i = 0; i < n; ++i) {
        nxt[pos[A[i]]-1] = pos[B[i]];
        nxt[pos[B[i]]-1] = pos[A[i]];
    }

    vector<int> cycle;
    cycle.reserve(n);
    int ans = 0;
    for (int s = 0; s < 2*n; ++s) {
        if (vis[s]) continue;
        for (int u = s, c = 1; ; ++c) {
            vis[u] = true;
            u = nxt[u];
            if (vis[u]) {
                cycle.push_back(c);
                break;
            } else if (u == 2*n) {
                ans = c;
                break;
            }
        }
    }
    sort(cycle.begin(), cycle.end());
    while (m--) {
        if (!cycle.empty()) {
            ans += cycle.back()+2;
            cycle.pop_back();
        } else {
            ++ans;
            cycle.push_back(1);
        }
    }
    printf("%d\n", ans);

    return 0;
}

Compilation message (stderr)

teleporters.cpp: In function 'int main()':
teleporters.cpp:12:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &n, &m);
     ~~~~~^~~~~~~~~~~~~~~~
teleporters.cpp:14:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &A[i], &B[i]);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~

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