Submission #57392

#	Time	Username	Problem	Language	Result	Execution time	Memory
57392		gabrielsimoes	Travelling Merchant (APIO17_merchant)	C++17	100 / 100	201 ms	2428 KiB

merchant

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

typedef pair<int, int> pii;
typedef long long ll;
const int MAXN = 101, MAXM = 9901, MAXK = 1001;
int N, M, K;
ll buy[MAXN][MAXK];
ll sell[MAXN][MAXK];

ll maxAns = 0;

bool reaches[MAXN][MAXN];
ll d[MAXN][MAXN];
ll gain[MAXN][MAXN];
ll dist[MAXN][MAXN];
bool ok[MAXN];

bool testPosCycle(ll x) {
    for (int i = 1; i <= N; i++) {
        for (int j = 1; j <= N; j++) {
            dist[i][j] = gain[i][j] - x * d[i][j];
        }
    }

    for (int k = 1; k <= N; k++) {
        for (int i = 1; i <= N; i++) {
            for (int j = 1; j <= N; j++) {
                if (i != j && reaches[i][k] && reaches[k][j]) {
                    dist[i][j] = max(dist[i][j], dist[i][k] + dist[k][j]);
                }
            }
        }
    }

    for (int i = 1; i <= N; i++) {
        for (int j = 1; j <= N; j++) {
            if (i != j && reaches[i][j] && reaches[j][i] && dist[i][j] + dist[j][i] >= 0) {
                return true;
            }
        }
    }

    return false;
}

int main() {
    scanf("%d%d%d", &N, &M, &K);
    for (int i = 1; i <= N; i++) {
        for (int k = 1; k <= K; k++) {
            scanf("%lld%lld", &buy[i][k], &sell[i][k]);
        }
    }

    for (int i = 1,a,b,c; i <= M; i++) {
        scanf("%d%d%d", &a, &b, &c);
        d[a][b] = c;
        reaches[a][b] = true;
    }

    for (int k = 1; k <= N; k++) {
        for (int i = 1; i <= N; i++) {
            for (int j = 1; j <= N; j++) {
                if (i != j && reaches[i][k] && reaches[k][j]) {
                    if (!reaches[i][j]) {
                        reaches[i][j] = true;
                        d[i][j] = d[i][k] + d[k][j];
                    } else {
                        d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
                    }
                }
            }
        }
    }

    for (int i = 1; i <= N; i++) {
        for (int j = 1; j <= N; j++) {
            for (int k = 1; k <= K; k++) {
                if (buy[i][k] != -1 && sell[j][k] != -1) {
                    gain[i][j] = max(gain[i][j], -buy[i][k] + sell[j][k]);
                }
            }
        }
    }

    for (int i = 1; i <= N; i++) {
        for (int j = 1; j <= N; j++) {
            if (i != j && reaches[i][j] && reaches[j][i]) {
                maxAns = max(maxAns, gain[i][j] + gain[j][i]);
            }
        }
    }

    ll l = 0, r = maxAns;
    while (l < r) {
        ll m = (l + r + 1LL) >> 1;
        if (testPosCycle(m)) l = m;
        else r = m-1;
    }

    printf("%lld\n", l);
}

Compilation message (stderr)

merchant.cpp: In function 'int main()':
merchant.cpp:48:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d%d", &N, &M, &K);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~
merchant.cpp:51:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%lld%lld", &buy[i][k], &sell[i][k]);
             ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
merchant.cpp:56:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d", &a, &b, &c);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 12 / 12
• Subtask 2: 21 / 21
• Subtask 3: 33 / 33
• Subtask 4: 34 / 34