ACM模板——网络流
1 #include<bits/stdc++.h> 2 #define _for(i,a,b) for(register int i = (a);i < b;i ++) 3 #define _rep(i,a,b) for(register int i = (a);i > b;i --) 4 #define INF 0x3f3f3f3f 5 #define MOD 100000000 6 #define maxn 1000003 7 #define pb push_back 8 #define debug() printf("Miku Check OK!\n") 9 typedef long long ll; 10 11 using namespace std; 12 typedef pair<int,int> P; 13 inline ll read() 14 { 15 ll ans = 0; 16 char ch = getchar(), last = ' '; 17 while(!isdigit(ch)) last = ch, ch = getchar(); 18 while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar(); 19 if(last == '-') ans = -ans; 20 return ans; 21 } 22 inline void write(ll x) 23 { 24 if(x < 0) x = -x, putchar('-'); 25 if(x >= 10) write(x / 10); 26 putchar(x % 10 + '0'); 27 } 28 int ver[maxn],Next[maxn],head[maxn],val[maxn]; 29 //incf[i]为i在此趟BFS流过的流量 30 int vis[maxn],incf[maxn],pre[maxn]; 31 int n,m,s,t,tot,maxflow; 32 void add(int x,int y,int w) 33 { 34 ver[++tot] = y,Next[tot] = head[x],head[x] = tot,val[tot] = w; 35 } 36 bool bfs() 37 { 38 memset(vis,0,sizeof(vis)); 39 queue<int> q; 40 q.push(s);vis[s] = 1; 41 incf[s] = INF; 42 while(!q.empty()) 43 { 44 int x = q.front();q.pop(); 45 for(int i = head[x]; i; i = Next[i]) 46 if(val[i]) 47 { 48 int y = ver[i]; 49 if(vis[y]) continue; 50 incf[y] = min(incf[x],val[i]); 51 pre[y] = i; 52 q.push(y);vis[y] = 1; 53 if(y==t) return true; 54 } 55 56 } 57 return false; 58 } 59 void update() 60 { 61 int x = t; 62 while(x != s) 63 { 64 int i = pre[x]; 65 val[i] -= incf[t]; 66 val[i^1] += incf[t]; 67 x = ver[i^1]; 68 69 } 70 maxflow += incf[t]; 71 } 72 int main() 73 { 74 n = read();m = read();s = read();t = read(); 75 tot = 1;maxflow = 0; 76 _for(i,1,m+1) 77 { 78 int x = read();int y = read();int c = read(); 79 add(x,y,c);add(y,x,0); 80 } 81 while(bfs()) update(); 82 write(maxflow); 83 return 0; 84 }
1 #include<bits/stdc++.h> 2 #define _for(i,a,b) for(register int i = (a);i < b;i ++) 3 #define _rep(i,a,b) for(register int i = (a);i > b;i --) 4 #define INF 0x3f3f3f3f 5 #define MOD 100000000 6 #define maxn 1000003 7 #define pb push_back 8 #define debug() printf("Miku Check OK!\n") 9 typedef long long ll; 10 11 using namespace std; 12 typedef pair<int,int> P; 13 inline ll read() 14 { 15 ll ans = 0; 16 char ch = getchar(), last = ' '; 17 while(!isdigit(ch)) last = ch, ch = getchar(); 18 while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar(); 19 if(last == '-') ans = -ans; 20 return ans; 21 } 22 inline void write(ll x) 23 { 24 if(x < 0) x = -x, putchar('-'); 25 if(x >= 10) write(x / 10); 26 putchar(x % 10 + '0'); 27 } 28 int ver[maxn],Next[maxn],head[maxn],val[maxn]; 29 int d[maxn]; 30 int n,m,s,t,tot,maxflow; 31 void add(int x,int y,int w) 32 { 33 ver[++tot] = y,Next[tot] = head[x],head[x] = tot,val[tot] = w; 34 } 35 bool bfs() 36 { 37 memset(d,0,sizeof(d)); 38 queue<int> q; 39 q.push(s);d[s] = 1; 40 while(!q.empty()) 41 { 42 int x = q.front();q.pop(); 43 for(int i = head[x]; i; i = Next[i]) 44 if(val[i] && !d[ver[i]]) 45 { 46 q.push(ver[i]); 47 d[ver[i]] = d[x]+1; 48 if(ver[i]==t) 49 return true; 50 } 51 } 52 return false; 53 } 54 int dinic(int x,int flow) 55 { 56 if(x==t) return flow; 57 // k为子节点增量 58 int rest = flow, k; 59 for(int i = head[x]; i && rest; i = Next[i]) 60 { 61 if(val[i] && d[ver[i]] == d[x]+1) 62 { 63 k = dinic(ver[i],min(rest,val[i])); 64 if(!k) d[ver[i]] = 0; 65 val[i] -= k; 66 val[i^1] += k; 67 rest -= k; 68 } 69 } 70 return flow - rest; 71 } 72 int main() 73 { 74 n = read();m = read();s = read();t = read(); 75 tot = 1;maxflow = 0; 76 _for(i,1,m+1) 77 { 78 int x = read();int y = read();int c = read(); 79 add(x,y,c);add(y,x,0); 80 } 81 int flow = 0; 82 while(bfs()) 83 while(flow = dinic(s,INF)) 84 maxflow += flow; 85 write(maxflow); 86 return 0; 87 }
#include<bits/stdc++.h> #define _for(i,a,b) for(register int i = (a);i < b;i ++) #define _rep(i,a,b) for(register int i = (a);i > b;i --) #define INF 0x3f3f3f3f #define MOD 100000000 #define maxn 100003 #define pb push_back #define debug() printf("Miku Check OK!\n") typedef long long ll; using namespace std; typedef pair<int,int> P; inline ll read() { ll ans = 0; char ch = getchar(), last = ' '; while(!isdigit(ch)) last = ch, ch = getchar(); while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar(); if(last == '-') ans = -ans; return ans; } inline void write(ll x) { if(x < 0) x = -x, putchar('-'); if(x >= 10) write(x / 10); putchar(x % 10 + '0'); } int ver[maxn],Next[maxn],head[maxn],val[maxn],cost[maxn]; //incf[i]为i在此趟BFS流过的流量 int vis[maxn],incf[maxn],pre[maxn]; int n,m,s,t,tot,maxflow,ans; int d[maxn]; void add(int x,int y,int w,int c) { ver[++tot] = y,Next[tot] = head[x],head[x] = tot,val[tot] = w,cost[tot] = c; ver[++tot] = x,Next[tot] = head[y],head[y] = tot,val[tot] = 0,cost[tot] = -c; } bool spfa() { memset(vis,0,sizeof(vis)); memset(d,0x3f,sizeof(d)); queue<int> q; q.push(s); vis[s] = 1; d[s] = 0; incf[s] = INF; while(!q.empty()) { int x = q.front(); q.pop(); vis[x] = 0; for(int i = head[x]; i; i = Next[i]) if(val[i]) { int y = ver[i]; if(d[y] > d[x] + cost[i]) { d[y] = d[x] + cost[i]; incf[y] = min(incf[x],val[i]); pre[y] = i; if(!vis[y]) vis[y] = 1,q.push(y); } } } if(d[t]==INF) return false; return true; } void update() { int x = t; while(x != s) { int i = pre[x]; val[i] -= incf[t]; val[i^1] += incf[t]; x = ver[i^1]; } maxflow += incf[t]; ans += d[t] * incf[t]; } int main() { n = read(); m = read(); s = 1; t = n+n; tot = 1; maxflow = 0; add(1,1+n,INF,0); add(n,n+n,INF,0); _for(i,2,n) add(i,i+n,1,0); _for(i,1,m+1) { int x = read(); int y = read(); int c = read(); add(x+n,y,1,c); } while(spfa()) update(); printf("%d %d",maxflow,ans); return 0; }
