92 lines
1.8 KiB
C++
92 lines
1.8 KiB
C++
#include <cstdio>
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#include <queue>
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#include <algorithm>
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using namespace std;
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const int inf = 1000000000;
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int map[1010][1010];
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int n, p;
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bool flag[1010];
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int dis[1010];
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void spfa()
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{
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for(int i = 1; i <= n ;++i)
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{
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flag[i] = false;
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dis[i] = inf;
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}
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dis[2] = 0;
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flag[2] = true;
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queue<int> que;
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que.push(2);
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while(!que.empty())
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{
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int now = que.front();
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que.pop();
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flag[now] = false;
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for(int i = 1; i <= n ;++i)
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{
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if(dis[i] > dis[now] + map[now][i])
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{
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dis[i] = dis[now] + map[now][i];
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if(!flag[i])
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{
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flag[i] = true;
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que.push(i);
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}
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}
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}
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}
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}
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int cou[1010];
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void dfs(int now)
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{
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if(now == 2)
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{
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cou[2] = 1;
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return;
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}
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int result(0);
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for(int i = 1; i <= n ;++i)
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{
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if(map[now][i] != inf && dis[i] < dis[now])
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{
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if(cou[i] >= 0)
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{
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result += cou[i];
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}
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else
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{
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dfs(i);
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result += cou[i];
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}
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}
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}
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cou[now] = result;
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}
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int main()
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{
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int a, b, dist;
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while(scanf("%d", &n) != EOF)
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{
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if(!n)
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break;
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scanf("%d", &p);
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for(int i = 0; i <= n; ++i)
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for(int j = 1; j <= n;++j)
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map[i][j] = inf;
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for(int i= 0; i < p; ++i)
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{
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scanf("%d %d %d", &a, &b, &dist);
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map[a][b] = map[b][a] = dist;
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}
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spfa();
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for(int i = 1; i <= n;++i)
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{
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cou[i] = -1;
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}
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dfs(1);
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printf("%d\n", cou[1]);
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}
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return 0;
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}
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