#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <cmath>#include <string>#include <map>#include <stack>#include <vector>#include <set>#include <queue>#pragma comment (linker,"/STACK:102400000,102400000")#define MAXN 1005#define MAXM 10005#define mod 1000000009#define INF 0x3f3f3f3f#define pi acos(-1.0)#define eps 1e-6#define lson rt<<1,l,mid#define rson rt<<1|1,mid+1,r#define FRE(i,a,b) for(i = a; i <= b; i++)#define FREE(i,a,b) for(i = a; i >= b; i–)#define FRL(i,a,b) for(i = a; i < b; i++)#define FRLL(i,a,b) for(i = a; i > b; i–)#define mem(t, v) memset ((t) , v, sizeof(t))#define sf(n)scanf("%d", &n)#define sff(a,b) scanf("%d %d", &a, &b)#define sfff(a,b,c) scanf("%d %d %d", &a, &b, &c)#define pfprintf#define DBGpf("Hi\n")typedef long long ll;using namespace std;struct Edge{int to,next,cap,flow;}edge[MAXM];int tol;int head[MAXN];int gap[MAXN],dep[MAXN],pre[MAXN],cur[MAXN];void init(){tol=0;memset(head,-1,sizeof(head));}//加边，单向图三个参数，双向图四个参数void addedge(int u,int v,int w,int rw=0){edge[tol].to=v; edge[tol].cap=w; edge[tol].next=head[u];edge[tol].flow=0; head[u]=tol++;edge[tol].to=u; edge[tol].cap=rw; edge[tol].next=head[v];edge[tol].flow=0; head[v]=tol++;}//输入参数：起点，终点，点的总数//点的编号没有影响，，只要输入点的总数int sap(int start,int end,int N){memset(gap,0,sizeof(gap));memset(dep,0,sizeof(dep));memcpy(cur,head,sizeof(head));int u=start;pre[u]=-1;gap[0]=N;int ans=0;while (dep[start]<N){if (u==end){int Min=INF;for (int i=pre[u];i!=-1;i=pre[edge[i^1].to])if (Min>edge[i].cap-edge[i].flow)Min=edge[i].cap-edge[i].flow;for (int i=pre[u];i!=-1;i=pre[edge[i^1].to]){edge[i].flow+=Min;edge[i^1].flow-=Min;}u=start;ans+=Min;continue;}bool flag=false;int v;for (int i=cur[u];i!=-1;i=edge[i].next){v=edge[i].to;if (edge[i].cap-edge[i].flow && dep[v]+1==dep[u]){flag=true;cur[u]=pre[v]=i;break;}}if (flag){u=v;continue;}int Min=N;for (int i=head[u];i!=-1;i=edge[i].next)if (edge[i].cap-edge[i].flow && dep[edge[i].to]<Min){Min=dep[edge[i].to];cur[u]=i;}gap[dep[u]]–;if (!gap[dep[u]]) return ans;dep[u]=Min+1;gap[dep[u]]++;if (u!=start) u=edge[pre[u]^1].to;}return ans;}struct EDGE{int u,v,w,next;}E1[MAXM],E2[MAXM];int n,m,k,num1,num2;int head1[MAXN],head2[MAXN],dist1[MAXN],dist2[MAXN],inq[MAXN];void init2(){num1=0;num2=0;memset(head1,-1,sizeof(head1));memset(head2,-1,sizeof(head2));}void add1(int u,int v){E1[num1].u=u; E1[num1].v=v; E1[num1].w=1; E1[num1].next=head1[u]++; head1[u]=num1++;}void add2(int u,int v){E2[num2].u=u; E2[num2].v=v; E2[num2].w=1; E2[num2].next=head2[u]++; head2[u]=num2++;}void spfa(int s,int* head,int* dist,EDGE * E){queue<int>Q;memset(inq,0,sizeof(inq));dist[s]=0;inq[s]=1;Q.push(s);while (!Q.empty()){int u=Q.front();Q.pop();for (int i=head[u];i+1;i=E[i].next){int v=E[i].v;if (dist[v]>dist[u]+E[i].w){dist[v]=dist[u]+E[i].w;if (!inq[v]){inq[v]=1;Q.push(v);}}}}}int main(){int i,j,u,v;while (scanf("%d%d%d",&n,&m,&k)){if (n==0&&m==0&&k==0) break;init();init2();for (i=0;i<m;i++){scanf("%d%d",&u,&v);add1(u,v);add2(v,u);}memset(dist1,INF,sizeof(dist1));memset(dist2,INF,sizeof(dist2));spfa(1,head1,dist1,E1);spfa(n,head2,dist2,E2);for (i=0;i<num1;i++){if (dist1[E1[i].u]+dist2[E1[i].v]<k)addedge(E1[i].u+n,E1[i].v,INF);}for (i=1;i<=n;i++) addedge(i,i+n,1);printf("%d\n",sap(n+1,n,2*n));}return 0;}
从哪里跌倒就会从哪里爬起来,让我们一起努力吧
