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传送门:https://pintia.cn/problem-sets/994805342720868352/problems/994805489282433024
解:
迪杰斯特拉+DFS(模板)
- #include <cstdio>
- #include <climits>
- #include <cstring>
- #include <vector>
- #include <algorithm>
- using namespace std;
- const int maxn = 510;
- int c_max, n, sp, m;
- int pw[maxn];
- int d[maxn];
- bool vis[maxn];
- int G[maxn][maxn];
- vector<int> pre[maxn];
- void DJS(void)
- {
- fill(d, d + maxn, INT_MAX);
- memset(vis, false, sizeof(vis));
- d[0] = 0;
- for (int i = 0; i < n; i++)
- {
- int u = -1, min = INT_MAX;
- for (int j = 0; j <= n; j++)
- if (!vis[j] && d[j] < min) min = d[u = j];
- if (u == -1) return;
- vis[u] = true;
- for (int v = 1; v <= n; v++)
- {
- if (vis[v] || G[u][v] == INT_MAX) continue;
- if (G[u][v] + d[u] < d[v])
- {
- d[v] = G[u][v] + d[u];
- pre[v].clear();
- pre[v].push_back(u);
- }
- else if (G[u][v] + d[u] == d[v])
- pre[v].push_back(u);
- }
- }
- }
- vector<int> path, temp_path;
- int send = INT_MAX, back = INT_MAX;
- void DFS(int id)
- {
- if (!id)
- {
- int sen = 0, bac = 0;
- for (int i = temp_path.size() - 1; i >= 0; i--)
- {
- bac += pw[temp_path[i]];
- if (bac < 0)
- {
- sen -= bac;
- bac = 0;
- }
- }
- if (sen < send || (sen == send && bac < back))
- {
- path = temp_path;
- send = sen;
- back = bac;
- }
- }
- temp_path.push_back(id);
- for (int i = 0; i < pre[id].size(); i++)
- DFS(pre[id][i]);
-
- temp_path.pop_back();
- }
- int main(void)
- {
- // freopen("input.txt", "r", stdin);
- scanf("%d %d %d %d", &c_max, &n, &sp, &m);
- for (int i = 1; i <= n; i++)
- {
- scanf("%d", pw + i);
- pw[i] -= c_max / 2;
- }
-
- fill(G[0], G[0] + maxn * maxn, INT_MAX);
-
- while (m--)
- {
- int a, b, l;
- scanf("%d %d %d", &a, &b, &l);
- G[a][b] = G[b][a] = l;
- }
- DJS();
- DFS(sp);
- printf("%d 0", send);
- for (int i = path.size() - 1; i >= 0; i--)
- printf("->%d", path[i]);
- printf(" %d", back);
- return 0;
- }
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