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48 lines
1.2 KiB
C++
48 lines
1.2 KiB
C++
#define _CRT_SECURE_NO_WARNINGS
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#define _SILENCE_CXX17_C_HEADER_DEPRECATION_WARNING
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#include <bits/stdc++.h>
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using namespace std;
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const int N = 1005, M = 10050;
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int n, m;
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int adj[N], nxt[M << 1], to[M << 1], len[M << 1], ecnt;
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int dis[N];
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inline void addEdge(int f, int t, int l)
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{
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ecnt++;
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to[ecnt] = t;
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len[ecnt] = l;
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nxt[ecnt] = adj[f];
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adj[f] = ecnt;
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}
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int inq[N], que[M];
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void spfa(int s)
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{
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memset(inq, 0, sizeof(inq));
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memset(dis, 0x3f3f3f3f, sizeof(dis));
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int h, t, x;
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h = t = x = 0;
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for (dis[s] = 0, que[t++] = s, inq[s] = true; h ^ t; inq[que[h++]] = false)
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for (int cur = adj[que[h]]; cur; cur = nxt[cur])
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if (dis[to[cur]] > dis[que[h]] + len[cur])
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{
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dis[to[cur]] = dis[que[h]] + len[cur];
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if (!inq[to[cur]]) que[t++] = to[cur], inq[to[cur]] = true;
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}
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}
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int main()
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{
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while (scanf("%d%d", &n, &m), n | m)
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{
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memset(adj, 0, sizeof(adj)), ecnt = 0;
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for (int i = 0, a, b, c; i < m; i++)
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{
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scanf("%d%d%d", &a, &b, &c);
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addEdge(a, b, c);
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addEdge(b, a, c);
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}
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spfa(1);
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printf("%d\n", dis[n]);
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}
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return 0;
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}
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