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50 lines
1.1 KiB
C++
50 lines
1.1 KiB
C++
#include <bits/stdc++.h>
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using namespace std;
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int n, m, dist1[1005], dist2[1005], backup[1005];
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struct node {
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int s, t, w;
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} g[10005];
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void bellman_ford1() {
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memset(dist1, 0x3f, sizeof(dist1));
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dist1[1] = 0;
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for (int i = 1; i <= n; i++) {
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memcpy(backup, dist1, sizeof(dist1));
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for (int j = 1; j <= m; j++) {
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dist1[g[j].t] = min(dist1[g[j].t], backup[g[j].s] + g[j].w);
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}
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}
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}
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void bellman_ford2() {
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memset(dist2, 0x3f, sizeof(dist2));
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dist2[n] = 0;
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for (int i = 1; i <= n; i++) {
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memcpy(backup, dist2, sizeof(dist2));
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for (int j = 1; j <= m; j++) {
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dist2[g[j].t] = min(dist2[g[j].t], backup[g[j].s] + g[j].w);
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}
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}
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}
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int main() {
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cin >> n >> m;
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for (int i = 1; i <= m; i++) {
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cin >> g[i].s >> g[i].t >> g[i].w;
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g[i].w = -g[i].w;
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}
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bellman_ford1();
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for (int i = 1; i <= m; i++) {
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if (dist1[g[i].t] > dist1[g[i].s] + g[i].w) {
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cout << "Forever love" << endl;
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exit(0);
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}
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}
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bellman_ford2();
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cout << min(dist1[n], dist2[1]) << endl;
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return 0;
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}
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