【BZOJ2229】[Zjoi2011]最小割【Gomory-Hu树】

【题目链接】

可以参考《浅谈无向图最小割问题的一些算法及应用》王文涛

然而并没有建树

/* Telekinetic Forest Guard */
#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

const int maxn = 155, maxm = 30005, maxq = 10000, inf = 0x3f3f3f3f;

int n, m, head[maxn], cur[maxn], cnt, depth[maxn], bg, ed, q[maxq], ans[maxn][maxn], id[maxn], tmp[maxn], mark[maxn], clo;

struct _edge {
int v, w, next;
} g[maxm << 1];

inline int iread() {
int f = 1, x = 0; char ch = getchar();
for(; ch < '0' || ch > '9'; ch = getchar()) f = ch == '-' ? -1 : 1;
for(; ch >= '0' && ch <= '9'; ch = getchar()) x = x * 10 + ch - '0';
return f * x;
}

inline void add(int u, int v, int w) {
g[cnt] = (_edge){v, w, head[u]};
head[u] = cnt++;
}

inline void insert(int u, int v, int w) {
add(u, v, w); add(v, u, 0);
}

inline bool bfs() {
for(int i = 1; i <= n; i++) depth[i] = -1;
int h = 0, t = 0, u, i; depth[q[t++] = bg] = 1;
while(h != t) for(i = head[u = q[h++]]; ~i; i = g[i].next) if(g[i].w && !~depth[g[i].v]) {
depth[g[i].v] = depth[u] + 1;
if(g[i].v == ed) return 1;
q[t++] = g[i].v;
}
return 0;
}

inline int dfs(int x, int flow) {
if(x == ed) return flow;
int left = flow;
for(int i = cur[x]; ~i; i = g[i].next) if(g[i].w && depth[g[i].v] == depth[x] + 1) {
int tmp = dfs(g[i].v, min(left, g[i].w));
left -= tmp; g[i].w -= tmp; g[i ^ 1].w += tmp;
if(g[i].w) cur[x] = i;
if(!left) return flow;
}
if(left == flow) depth[x] = -1;
return flow - left;
}

inline int dinic() {
int res = 0;
while(bfs()) {
for(int i = 1; i <= n; i++) cur[i] = head[i];
res += dfs(bg, inf);
}
return res;
}

inline void go(int x) {
mark[x] = clo;
for(int i = head[x]; ~i; i = g[i].next) if(g[i].w && mark[g[i].v] != clo)
go(g[i].v);
}

inline void solve(int l, int r) {
if(l == r) return;
for(int i = 0; i < cnt; i += 2) g[i].w += g[i ^ 1].w, g[i ^ 1].w = 0;
bg = id[l]; ed = id[r]; int cut = dinic();
clo++; go(bg);
for(int i = 1; i <= n; i++) if(mark[i] == clo) for(int j = 1; j <= n; j++) if(mark[j] != clo)
ans[i][j] = ans[j][i] = min(ans[i][j], cut);
int h1 = l, h2 = r;
for(int i = l; i <= r; i++) tmp[mark[id[i]] == clo ? h1++ : h2--] = id[i];
for(int i = l; i <= r; i++) id[i] = tmp[i];
solve(l, h1 - 1); solve(h2 + 1, r);
}

int main() {
for(int T = iread(); T; T--) {
n = iread(); m = iread();
for(int i = 1; i <= n; i++) id[i] = i, head[i] = -1; cnt = 0;
memset(ans, 0x3f, sizeof(ans));
for(int i = 1; i <= m; i++) {
int u = iread(), v = iread(), w = iread();
insert(u, v, w); insert(v, u, w);
}

solve(1, n);

for(int Q = iread(); Q; Q--) {
int x = iread(), res = 0;
for(int i = 1; i <= n; i++) for(int j = i + 1; j <= n; j++)
res += (ans[i][j] <= x);
printf("%d\n", res);
}
printf("\n");
}
return 0;
}