kuangbin_ShortPath E (POJ 1860)

第一次做判环 然后RE了五次 死在了奇怪的点

memset(vis, 0, sizeof dis);

memset(dis, 0, sizeof vis);

什么鬼?? 什么鬼??

其实代码本身还是不难的 就是spfa另外开个数组记录入队次数

spfa不用写cmp真是太好了 operator什么的真的搞不清

#include <iostream>
#include <string>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <queue>
#include <map>
#include <vector>
#include <set>
#include <algorithm>
#define INF 0x3F3F3F3F
using namespace std;

struct Node{
double c;//commission
double r;//rate
int point;
int next;
}node[1010];
int size, head[1010];
int n, m, s;
double sq;

void add(int from, int to, double rate, double commission)
{
node[size].r = rate;
node[size].c = commission;
node[size].point = to;
node[size].next = head[from];
head[from] = size++;
}
bool spfa()
{
double dis[1010];
int count[1010];
bool vis[1010];
memset(count, 0, sizeof count);
memset(dis, 0, sizeof dis);
memset(vis, false, sizeof vis);

queue<int> q;
q.push(s);
dis[s] = sq;
vis[s] = true;
while(!q.empty()){
int u = q.front();
q.pop();
vis[u] = false;
for(int i = head[u]; ~i; i = node[i].next){
int j = node[i].point;
if(dis[j] < (dis[u] - node[i].c) * node[i].r){
dis[j] = (dis[u] - node[i].c) * node[i].r;
if(!vis[j]){
q.push(j);
vis[j] = true;
count[j]++;
if(count[j] > n) return true;
}
}
}
}
return false;
}
int main()
{
while(~scanf("%d%d%d%lf", &n, &m, &s, &sq)){
size = 0;
memset(head, -1, sizeof head);
while(m--){
int from, to;
double r1, c1, r2, c2;
scanf("%d%d%lf%lf%lf%lf", &from, &to, &r1, &c1, &r2, &c2);
add(from, to, r1, c1);
add(to, from, r2, c2);
}
if(spfa()) puts("YES");
else puts("NO");
}
return 0;
}