HDU 1874 图论模板复习

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裸的最短路问题，复习一下图论的模板

http://acm.hdu.edu.cn/showproblem.php?pid=1874

SPFA 数组版本

#include<iostream>#include<vector>#include<queue>#include<cstdio>#define INF 99999999using namespace std;const int maxn = 222;int mapp[maxn][maxn],n,m;int vis[maxn], dis[maxn];int SPFA(int st,int end){    for(int i=0;i<=n;i++){ // 初始化        dis[i] = INF; vis[i] = 0;//G[i].clear();    }    queue<int>Q;    dis[st] = 0;     vis[st] = 1; //起始点距离为0， 标记上    Q.push(st);    while(!Q.empty()){        int vex = Q.front(); Q.pop();        vis[vex] = 0; //          for(int i=0;i<n;i++){            if( dis[i] > mapp[vex][i] + dis[vex]){                dis[i] = mapp[vex][i] + dis[vex];                if(!vis[i]){                    vis[i] = 1;                    Q.push(i);                }            }        }    }    return dis[end];}int main(){    while(scanf("%d%d",&n,&m)!=EOF){        for(int i=0;i<n;i++)            for(int j=0;j<n;j++)                mapp[i][j] = INF;        int a,b,c;        for(int i=0;i<m;i++){            scanf("%d%d%d",&a,&b,&c);            if(c < mapp[a][b])                mapp[a][b] = mapp[b][a] = c;        }        int s,e;         scanf("%d%d",&s,&e);        int ans = SPFA(s,e);        if(ans < INF) printf("%d\n",ans);        else            printf("-1\n");    }}

SPFA vector版本（邻接链表）

#include<iostream>#include<vector>#include<queue>#include<cstdio>#define INF 0xfffffffusing namespace std;struct node{    int v,len;    node(int v = 0,int len=0):v(v),len(len){}};const int maxn = 222;vector<node>G[maxn];int dis[maxn];int vis[maxn];int n,m;void init(){    for(int i=0;i<maxn;i++){        dis[i] = INF; vis[i] = 0;G[i].clear();    }}int SPFA(int st,int end){    vis[st] = 1; queue<int>Q;    dis[st] = 0;    Q.push(st);    while(!Q.empty()){        int vex = Q.front(); Q.pop();        vis[vex] = 0;        for(int i=0;i<G[vex].size();i++){            int v = G[vex][i].v;            if( dis[v] > G[vex][i].len + dis[vex] ){                dis[v] = G[vex][i].len + dis[vex];                if(!vis[v]){                    vis[v] = 1;                    Q.push(v);                }            }        }    }    return dis[end];}int main(){    int n,m;    while(scanf("%d%d",&n,&m)!=EOF){        init(); //        for(int i=0;i<m;i++){            int a,b,c; scanf("%d%d%d",&a,&b,&c);            G[a].push_back(node(b,c));            G[b].push_back(node(a,c));        }        int s,e; scanf("%d%d",&s,&e);        int ans = SPFA(s,e);        if(ans == INF) printf("-1\n");        else            printf("%d\n",ans);    }}

Floyed

#include<iostream>#include<vector>#include<queue>#include<cstdio>#define INF 0xfffffffusing namespace std;const int maxn = 222;int n,m;int map[maxn][maxn];void floyed(){ //k ,i ,jfor(int k=0;k<n;k++)for(int i=0;i<n;i++)for(int j=0;j<n;j++)if(map[i][j] > map[i][k] + map[k][j])map[i][j] = map[i][k] + map[k][j];}int main(){    while(scanf("%d%d",&n,&m)!=EOF){for(int i=0;i<n;i++)for(int j=0;j<n;j++)if(i == j) map[i][j] = 0;else map[i][j] = INF;int a,b,c;        for(int i=0;i<m;i++){            scanf("%d%d%d",&a,&b,&c);if(c < map[a][b]) //重边map[a][b] = map[b][a] = c;        }int s,e; scanf("%d%d",&s,&e);floyed();if(map[s][e] == INF)printf("-1\n");        elseprintf("%d\n",map[s][e]);    }return 0;}

Dijkstra vector版本（邻接链表）

#include<iostream>#include<vector>#include<queue>#include<cstdio>#include<cstring>#define INF 0xfffffffusing namespace std;const int maxn = 222;int n,m;int map[maxn][maxn];int dis[maxn];bool vis[maxn];struct node{    int v,len;    node(int v=0,int len=0):v(v),len(len){}};vector<node>G[maxn];int dijkstra(int st,int end){    vis[st] = 1;    for(int i=0;i<G[st].size();i++){        int vex = G[st][i].v;        dis[vex] = min(dis[vex],G[st][i].len); // 消除重边    }    dis[st] = 0;    for(int num = 1;num<n;num++){ //找到其余的n-1个点        int tmp = INF, k = -1;        for(int i=0;i<n;i++){ //找到 距离最近的一个节点            if(!vis[i] && tmp > dis[i] ){                tmp = dis[i];                k = i;            }        }

<pre code_snippet_id="1614353" snippet_file_name="blog_20160317_4_7291603" name="code" class="cpp">        if(k == -1) break;

vis[k] = true; for(int i=0;i<G[k].size();i++){ int vex = G[k][i].v; if(!vis[vex] && dis[vex] > dis[k] + G[k][i].len ){ dis[vex] = dis[k] + G[k][i].len; } } } return dis[end];}int main(){ while(scanf("%d%d",&n,&m)!=EOF){ for(int i=0;i<=n;i++){ G[i].clear(); vis[i] = 0; dis[i] = INF; } int a,b,c; for(int i=0;i<m;i++){ scanf("%d%d%d",&a,&b,&c); G[a].push_back(node(b,c)); G[b].push_back(node(a,c)); } int s,e; scanf("%d%d",&s,&e); int ans = dijkstra(s,e); if(ans == INF) printf("-1\n"); else printf("%d\n",ans); } return 0;}

Dijkstra 邻接矩阵

#include<iostream>#include<vector>#include<queue>#include<cstdio>#include<cstring>#define INF 0xfffffffusing namespace std;const int maxn = 222;int n,m;int map[maxn][maxn];int dis[maxn];bool vis[maxn];int dijkstra(int st,int end){memset(vis,0,sizeof(vis));vis[st] = 1;for(int i=0;i<n;i++){dis[i] = map[st][i];}dis[st] = 0;for(int num = 1;num<n;num++){ //找到其余的n-1个点int tmp = INF, k = -1;for(int i=0;i<n;i++){if(!vis[i] && tmp > dis[i]){tmp = dis[i];k = i;}}

<pre code_snippet_id="1614353" snippet_file_name="blog_20160317_5_7117662" name="code" class="cpp">if(k== -1) break; // 当前没有找到最短的节点

vis[k] = true;for(int i=0;i<n;i++)if(!vis[i] && dis[i] > dis[k] + map[k][i] )dis[i] = dis[k] + map[k][i]; }return dis[end];}int main(){ while(scanf("%d%d",&n,&m)!=EOF){for(int i=0;i<n;i++)for(int j=0;j<n;j++)map[i][j] = (i == j)? 0:INF; int a,b,c; for(int i=0;i<m;i++){ scanf("%d%d%d",&a,&b,&c);if(c< map[a][b])map[a][b] = map[b][a] = c; }int s,e; scanf("%d%d",&s,&e);int ans = dijkstra(s,e);if(ans == INF)printf("-1\n"); elseprintf("%d\n",ans); }return 0;}

Dijkstra 堆优化

#include <cstdio>#include <vector>#include <queue>#include <algorithm>#define MAXN 200 + 10#define INF 0xffffffusing namespace std;struct node{    int v, len;    bool operator < (const node & t) const{        return len > t.len;    }    node(int v = 0, int len = 0):v(v), len(len){}};vector<node> G[MAXN];bool vis[MAXN];int dis[MAXN];void Init(int n){    for(int i = 0; i < n; i++){        vis[i] = false;        G[i].clear();        dis[i] = INF;    }}int dijstra_heap(int s,int t,int n){    priority_queue<node>Q;    dis[s] = 0;    Q.push(node(s,0));    while(!Q.empty()){        node now = Q.top();        Q.pop();        int v = now.v;        if(vis[v]) continue;        vis[v] = true;        for(int i=0;i<G[v].size();i++){            int v2 = G[v][i].v; int len = G[v][i].len;            if(!vis[v2] && dis[v] + len <dis[v2]){                dis[v2] = dis[v] + len ;                Q.push(node(v2,dis[v2])); //讲 dis[v2]放入堆中，利用logn的效率找到                                            //距离最短的节点            }        }    }    return dis[t];}int main(){    int n, m;    int v1, v2, x, s, t;    while(scanf("%d%d", &n, &m) != EOF){        Init(n);        for(int i = 0; i < m; i++){            scanf("%d%d%d", &v1, &v2, &x);            G[v1].push_back(node(v2, x));            G[v2].push_back(node(v1, x));        }        scanf("%d%d", &s, &t);        int ans = dijstra_heap(s, t, n);        if(ans == INF)            printf("-1\n");        else            printf("%d\n", ans);    }    return 0;}

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