Is the Information Reliable?

Description

The galaxy war between the Empire Draco and the Commonwealth of Zibu broke out 3 years ago. Draco established a line of defense called Grot. Grot is a straight line with N defense stations. Because of the cooperation of the stations, Zibu’s Marine Glory cannot march any further but stay outside the line.

A mystery Information Group X benefits form selling information to both sides of the war. Today you the administrator of Zibu’s Intelligence Department got a piece of information about Grot’s defense stations’ arrangement from Information Group X. Your task is to determine whether the information is reliable.

The information consists of M tips. Each tip is either precise or vague.

Precise tip is in the form of P A B X, means defense station A is X light-years north of defense station B.

Vague tip is in the form of V A B, means defense station A is in the north of defense station B, at least 1 light-year, but the precise distance is unknown.

Input

There are several test cases in the input. Each test case starts with two integers N (0 < N ≤ 1000) and M (1 ≤ M ≤ 100000).The next M line each describe a tip, either in precise form or vague form.

Output

Output one line for each test case in the input. Output “Reliable” if It is possible to arrange N defense stations satisfying all the M tips, otherwise output “Unreliable”.

Sample Input

3 4
P 1 2 1
P 2 3 1
V 1 3
P 1 3 1
5 5
V 1 2
V 2 3
V 3 4
V 4 5
V 3 5

Sample Output

Unreliable
Reliable

这个题分为模糊查找和精确查找，P是精确，V是模糊，精确地就是==，即s[v]-s[u]=w(s[v]-s[u]>=w&&s[v]-s[u]<=w),当v的时候因为至少为1，所以s[v]-s[u]>=1,因为只是判断负环，所以我将其转化成>=

<pre name="code" class="cpp">#include <iostream>
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define oo 1<<28
#include<queue>
struct node
{
    int u;
    int v;
    int w;
    int next;
} edge[1100000];
int n,m;
using namespace std;
int cnt;
int dis[5000];
int head[5000];
void add(int u,int v,int w)
{
    edge[cnt].u=u;
    edge[cnt].v=v;
    edge[cnt++].w=w;
}
void bellman_ford()
{
    int flag;
    memset(dis,-1,sizeof(dis));
    for(int i=1;i<=n+1;i++)
    {
        flag=0;
        for(int j=0;j<cnt;j++)
        {
            int v=edge[j].v;
            int u=edge[j].u;
            int w=edge[j].w;
            if(dis[v]<dis[u]+w)
            {
                dis[v]=dis[u]+w;
                flag=1;
            }
        }
        if(!flag)//dis没有更新
            break;
    }
    if(!flag) printf("Reliable\n");
    else printf("Unreliable\n");
}
int main()
{
    int i,j;
    char str[1000];
    while(~scanf("%d%d",&n,&m))
    {
        int u,v,w;
        cnt=0;
        memset(head,-1,sizeof(head));
        for(i=1; i<=m; i++)
        {

            scanf("%s",&str);
            if(str[0]=='P')
            {
                scanf("%d%d%d",&u,&v,&w);//精确查找双向边
                add(u,v,w);
                add(v,u,-w);
            }
            else if(str[0]=='V')
            {
                scanf("%d%d",&u,&v);//模糊查找
                add(u,v,1);
            }
        }
        bellman_ford();
    }
    return 0;
}