OJ-Problems-Source/POJ/1947_infnty.cpp

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#include <cstdio>
#include <cstring>
#include <cassert>
#include <algorithm>
#include <sstream>
#include <vector>
using namespace std;
#define REP(i,n) for(int _REP_N=(n),i=0;i<_REP_N;i++)
int N, parent[200], kid[200], sib[200], memo[200][200], INF=1<<25;
vector<int> adj[200];
int g(int x, int k);
int f(int x, int k) {
int &res = memo[x][k];
if (res != -1) return res;
if (x == 0) return res = (k==0 ? 0 : INF);
assert(2 <= x && x <= N && k >= 0);
res = 1 + f(sib[x], k);
for (int u = 1; u <= k; u++)
res <?= g(x, u) + f(sib[x], k-u);
return res;
}
int g(int x, int k) {
assert(1 <= x && x <= N && k >= 0);
int deg = adj[x].size() - (x==1 ? 0 : 1);
if (k == 0) return 0;
if (k == 1) return deg;
if (deg == 0) return INF;
return f(kid[x], k-1);
}
void dfs(int x, int p) {
parent[x] = p;
kid[x] = 0;
REP(i, adj[x].size()) {
int y = adj[x][i];
if (y != p) {
sib[y] = kid[x];
kid[x] = y;
dfs(y, x);
}
}
}
int main() {
int P;
scanf("%d %d", &N, &P);
REP(i, N-1) {
int x, y;
scanf("%d %d", &x, &y);
adj[x].push_back(y);
adj[y].push_back(x);
}
kid[0] = sib[0] = parent[0] = 0;
dfs(1, 0);
memset(memo, 0xff, sizeof(memo));
int res = INF;
for (int x = 1; x <= N; x++)
res <?= g(x,P) + (x==1 ? 0 : 1);
printf("%d\n", res);
}