hdu1142

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这道题纠结了好久~~~最后发现最短路的算法求错了~~~

可是以前用此代码AC了好几道题了~~~汗~~求指点~

先是最后ac代码：

#include <iostream>#include <cstdio>#include <queue>#include <cstring>#define INF 1000010010using namespace std;int d[1005];int vis[1005];int w[1005][1005];int s[1005];void init(int n){    memset(s,0,sizeof(s));    memset(vis,0,sizeof(vis));    int i,j;    for(i=0;i<=n;i++)    {        for(j=0;j<=n;j++)        {            w[i][j]=INF;            if(i==j)                w[i][j]=0;        }        d[i]=INF;    }}int DFS(int k,int n){    if(s[k])        return s[k];     if(k == 2)        return 1;    for(int i=1; i<=n; i++)     {         if(w[k][i]!=INF && d[k]>d[i])            s[k]+=DFS(i,n);   }    return s[k];}struct cmp{    bool operator()(int a,int b)    {        return a>b;    }};int main(){    int n,m;    while(scanf("%d",&n),n!=0)    {        init(n);        scanf("%d",&m);        int i,a,b,d1;        for(i=0;i<m;i++)        {            scanf("%d%d%d",&a,&b,&d1);            if(d1<w[a][b])                w[a][b]=w[b][a]=d1;        }        d[2]=0;        //priority_queue<int,vector<int>,cmp> q;        typedef pair<int,int> pii;        priority_queue<pii,vector<pii>,greater<pii> > q;        q.push(make_pair(d[2],2));        while(!q.empty())        {            pii t1=q.top();            q.pop();            int t=t1.second;            if(vis[t])                continue;            vis[t]=1;            for(i=1;i<=n;i++)            {                if(!vis[i]&&d[i]>d[t]+w[t][i])                {                    d[i]=d[t]+w[t][i];                    q.push(make_pair(d[i],i));                }            }        }        printf("%d\n",DFS(1,n));    }    return 0;}

然后是WA的代码：

#include <iostream>#include <cstdio>#include <queue>#include <cstring>#define INF 1000010010using namespace std;int d[1005];int vis[1005];int w[1005][1005];int s[1005];void init(int n){    memset(s,0,sizeof(s));    memset(vis,0,sizeof(vis));    int i,j;    for(i=0;i<=n;i++)    {        for(j=0;j<=n;j++)        {            w[i][j]=INF;            if(i==j)                w[i][j]=0;        }        d[i]=INF;    }}int DFS(int k,int n){    if(s[k])        return s[k];     if(k == 2)        return 1;    for(int i=1; i<=n; i++)     {         if(w[k][i]!=INF && d[k]>d[i])            s[k]+=DFS(i,n);   }    return s[k];}struct cmp{    bool operator()(int a,int b)    {        return d[a]>d[b];             //此处修改    }};int main(){    int n,m;    while(scanf("%d",&n),n!=0)    {        init(n);        scanf("%d",&m);        int i,a,b,d1;        for(i=0;i<m;i++)        {            scanf("%d%d%d",&a,&b,&d1);            if(d1<w[a][b])                w[a][b]=w[b][a]=d1;        }        d[2]=0;        priority_queue<int,vector<int>,cmp> q;         //此处修改        //typedef pair<int,int> pii;        //priority_queue<pii,vector<pii>,greater<pii> > q;        q.push(2);        while(!q.empty())        {            int t=q.top();            q.pop();            //int t=t1.second;            if(vis[t])                continue;            vis[t]=1;            for(i=1;i<=n;i++)            {                if(!vis[i]&&d[i]>d[t]+w[t][i])                {                    d[i]=d[t]+w[t][i];                    q.push(i);              //此次修改~~                }            }        }        printf("%d\n",DFS(1,n));    }    return 0;}

感觉对的~~但是wa了难道priority queue 用法有误么~~

~~知道问题了~~原来是priority_queue有问题~看看实现就知道了~q.push().q.pop() 都会排序