最大流的ISAP算法，使用GAP优化
#include
#define maxint 0x3fffffff
#define maxn 3000
#define S 1
#define T N
//链表存图，使用反向弧指针
typedef struct Edge {
int vtx, cap, flow;
Edge *rev, *next;
Edge (){}
Edge (int vertex, int capacity, Edge* pt){
vtx = vertex; cap = capacity; flow = 0;
rev = NULL; next = [......]