【最短路】 HDOJ 1317 XYZZY

spfa巧妙的变形。。。

#include <iostream>  #include <queue>  #include <stack>  #include <map>  #include <set>  #include <bitset>  #include <cstdio>  #include <algorithm>  #include <cstring>  #include <climits>  #include <cstdlib>#include <cmath>#include <time.h>#define maxn 8005#define maxm 8005#define eps 1e-10#define mod 998244353#define INF 999999999#define lowbit(x) (x&(-x))#define mp mark_pair#define ls o<<1#define rs o<<1 | 1#define lson o<<1, L, mid  #define rson o<<1 | 1, mid+1, R  typedef long long LL;//typedef int LL;using namespace std;LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}// headint h[maxn], next[maxm], v[maxm], cost[maxm];int inq[maxn], dis[maxn], outq[maxn];int in[maxn], vis[maxn];queue<int> q;int n, m, cnt;void init(void){cnt = 0;memset(h, -1, sizeof h);memset(in, 0, sizeof in);memset(vis, 0, sizeof vis);memset(inq, 0, sizeof inq);memset(outq, 0, sizeof outq);for(int i = 0; i <= n; i++) dis[i] = -INF;}void addedges(int u, int vv, int c){next[cnt] = h[u], h[u] = cnt, v[cnt] = vv, cost[cnt] = c, cnt++;}void read(void){int a, b, c;for(a = 1; a <= n; a++) {scanf("%d%d", &c, &m);while(m--) scanf("%d", &b), addedges(a, b, c), in[b]++;}}bool spfa(int s){while(!q.empty()) q.pop();dis[s] = 100, q.push(s), inq[s] = 1;while(!q.empty()) {int u = q.front(); q.pop(), inq[u] = 0;if(outq[u] == n+1) continue;outq[u]++;if(outq[u] == n+1) dis[u] = INF;for(int e = h[u]; ~e; e = next[e])if(dis[v[e]] < dis[u] + cost[e] && dis[u] + cost[e] > 0) {if(v[e] == n) return true;dis[v[e]] = dis[u] + cost[e];if(!inq[v[e]]) inq[v[e]] = 1, q.push(v[e]);}}return false;}int main(void){while(scanf("%d", &n), ~n){init();read();if(spfa(1)) printf("winnable\n");else printf("hopeless\n");}return 0;}