hdu 3549 Flow Problem(最大流)

最大流模板题

EK

#include <stdio.h>#include <string.h>#include <algorithm>#include <queue>#include <iostream>using namespace std;#define tt printf("ewgaergasergs\n");const int N = 10005;struct node{    int nxt, w, v;}e[N];int head[100], re[100], pre[100];int cnt, n, m;queue<int> q;void init(){    cnt = 0;    memset( head, -1, sizeof( head ));}void add( int u, int v, int w){    e[cnt].v = v;    e[cnt].w = w;    e[cnt].nxt = head[u];    head[u] = cnt++;        e[cnt].v = u;    e[cnt].w = 0;    e[cnt].nxt = head[v];    head[v] = cnt++;}int EK(){    while( !q.empty() )        q.pop();    memset( pre, -1, sizeof( pre ));    q.push(1);    bool OK = 0;    while( !q.empty() )    {        int u = q.front();        q.pop();        for( int i = head[u]; ~i; i = e[i].nxt )        {            int to = e[i].v;            if( pre[to] == -1 && e[i].w > 0 )            {                pre[to] = u;                re[to] = i;                if( to == n )                {                    OK = 1;                    break;                }                else                    q.push(to);            }        }        if( OK )            break;    }    if( !OK )        return 0;    int minflow = 99999999;    int now = n;    //printf("%d\n", pre[1]);    while( 1 )    {        minflow = min( minflow, e[re[now]].w);        now = pre[now];        if( now == 1 )            break;    }    now = n;    while( 1 )    {        e[re[now]].w -= minflow;        e[re[now]^1].w += minflow;        now = pre[now];        if( now == 1 )            break;    }    return minflow;}int main(){    int tot, cas = 1;    scanf("%d\n", &tot);    for( ; cas <= tot; cas++ )    {        init();        scanf("%d%d", &n, &m);        int u, v, w;        while(m--)        {            scanf("%d%d%d", &u, &v, &w);            add(u, v, w);        }        int tmp, ans = 0;        while( tmp = EK() )        {            ans += tmp;        }        printf("Case %d: %d\n", cas, ans);    }    return 0;}/*514 51 2 401 4 202 4 202 3 303 4 10*/

SAP：

#include <map>#include <set>#include <queue>#include <stack>#include <vector>#include <cmath>#include <cstdio>#include <cstdlib>#include <cstring>#include <iostream>#include <algorithm>using namespace std;#define lson l, mid, rt << 1#define rson mid + 1, r, rt << 1 | 1#define ls rt << 1#define rs rt << 1 | 1#define pi acos(-1.0)#define eps 1e-8typedef long long ll;const int inf = 0x3f3f3f3f;const int N = 2000;const int E = 10005;struct node{int nxt, v, cap, w;}e[E];int n, m, nn;int st, ed;int cnt;int head[N];int dep[N];int cur[N];int gap[N];int pre[N];void init(){cnt = 0;memset( head, -1, sizeof( head ) );st = 1, ed = n, nn = n + 1;}void add( int u, int v, int w, int rw = 0 ){e[cnt].v = v;e[cnt].cap = w;e[cnt].w = 0;e[cnt].nxt = head[u];head[u] = cnt++;e[cnt].v = u;e[cnt].cap = rw;e[cnt].w = 0;e[cnt].nxt = head[v];head[v] = cnt++;}int isap(){memset( gap, 0, sizeof( gap ) );memset( dep, 0, sizeof( dep ) );memcpy( cur, head, sizeof head );int u = st;pre[u] = -1;gap[0] = nn;int flow = 0;while( dep[st] < nn ){if( u == ed ){int minn = inf, tmp;for( int i = pre[u]; ~i; i = pre[e[i^1].v] ){if( minn > e[i].cap - e[i].w ){minn = e[i].cap - e[i].w;}}for( int i = pre[u]; ~i; i = pre[e[i^1].v] ){e[i].w += minn;e[i^1].w -= minn;}u = st;flow += minn;}bool f = 0;int v;for( int i = cur[u]; ~i; i = e[i].nxt ){v = e[i].v;if( e[i].cap - e[i].w && dep[v]+1 == dep[u] ){f = 1;cur[u] = pre[v] = i;break;}}if( f ){u = v;continue;}int minn = nn;for( int i = head[u]; ~i; i = e[i].nxt ){if( e[i].cap - e[i].w && dep[e[i].v] < minn ){cur[u] = i;minn = dep[e[i].v];}}gap[dep[u]]--;if( !gap[dep[u]] )return flow;dep[u] = minn + 1;gap[dep[u]]++;if( u != st )u = e[pre[u]^1].v;}return flow;}int main(){int tot;scanf("%d", &tot);for( int ca = 1; ca <= tot; ++ca ){scanf("%d%d", &n, &m);init();int u, v, w;for( int i = 1; i <= m; ++i ){scanf("%d%d%d", &u, &v, &w);add( u, v, w );}int ans = isap();printf("Case %d: ", ca);printf("%d\n", ans);}}