poj 1364 King 差分约束

差分约束系统

写了两种解法

第一种是bellman-ford

第二种是spfa

 

 

#include <iostream>
#include<stdio.h>
#include<string.h>
using namespace std;
const int maxn=302;
const int inf=1<<29;
int e[maxn][maxn];
int n,m;

int dist[maxn];

int solve()
{
    for(int i=0;i<=n;i++)
    dist[i]=-inf;
    dist[0]=0;
    for(int k=0;k<=n;k++)
    for(int i=0;i<=n;i++)
    for(int j=0;j<=n;j++)
    if(e[i][j]+dist[i]>dist[j])
    dist[j]=e[i][j]+dist[i];
    for(int i=0;i<=n;i++)
    for(int j=0;j<=n;j++)
    if(e[i][j]+dist[i]>dist[j])
    return(1);
    return(0);
}

int main()
{
     freopen("in.txt","r",stdin);
    while(scanf("%d %d",&n,&m)!=EOF)
    {
        if(n==0) break;
        for(int i=0;i<=n;i++)
        for(int j=0;j<=n;j++) e[i][j]=-inf;
        char g[5];
        for(int i=1,a,b,c;i<=m;i++)
        {
            scanf("%d %d %s %d",&a,&b,g,&c);
            b+=a;
            if(g[0]=='g')
            e[a-1][b]=c+1;
            else
            e[b][a-1]=-c+1;
        }
        if(solve()) printf("successful conspiracy\n");
        else printf("lamentable kingdom\n");
    }
    return 0;
}

 

 

 

 

 

 

 

 

#include <iostream>
#include<stdio.h>
#include<string.h>
using namespace std;
const int maxn=302;
const int inf=1<<29;
int e[maxn][maxn];
int n,m;

int text[maxn],queue[1000001],front,end;
int dist[maxn],time[maxn];
int ture;

int spfa()
{
    int t=queue[front++];
    text[t]=0;
    for(int i=0;i<=n;i++)
    if(dist[t]+e[t][i]>dist[i])
    {

        dist[i]=dist[t]+e[t][i];
//        printf("%d %d\n",dist[i],i);
//        printf("%d\n",dist[i]);
        if(!text[i])
        {
            text[i]=1;
            queue[++end]=i;
            time[i]++;
            if(time[i]>n+2)
            {
                front=inf;
                ture=1;
                return(0);
            }
        }
    }
}

int solve()
{
    memset(text,0,sizeof(text));
    memset(time,0,sizeof(time));
    ture=0;
    for(int i=0;i<=n;i++)
    dist[i]=-inf;
    dist[n]=0;
    front=1,end=1;
    queue[front]=n;
    while(front<=end)
    spfa();
//    for(int i=1;i<=n;i++)
//    printf("%d ",dist[i]);
}

int main()
{
//    freopen("in.txt","r",stdin);
    while(scanf("%d %d",&n,&m)!=EOF)
    {
        if(n==0) break;
        n++;
        for(int i=0;i<=n;i++)
        for(int j=0;j<=n;j++) e[i][j]=-inf;
        char g[5];
        for(int i=1,a,b,c;i<=m;i++)
        {
            scanf("%d %d %s %d",&a,&b,g,&c);
            b+=a;
            if(g[0]=='g')
            e[a-1][b]=c+1;
            else
            e[b][a-1]=-c+1;
        }
        for(int i=0;i<=n;i++) e[n][i]=0;

        solve();
        if(ture) printf("successful conspiracy\n");
        else printf("lamentable kingdom\n");
    }
    return 0;
}