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Paste #BAl -- näytä pelkkänä tekstinä -- uusi tämän pohjalta

Värjäys: Tyyli: ensimmäinen rivinumero: Tabin korvaus: 

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#include <bits/stdc++.h>
#define F first
#define S second
#define X real()
#define Y imag()
using namespace std;
typedef long long ll;
typedef long double ld;
struct LPSolver {
    const ld eps=1e-9;
    const ld inf=1e30;
    int m, n;
    vector<int> N, B;
    vector<vector<ld> > D;
    LPSolver(vector<vector<ld> >& A, vector<ld>& b, vector<ld>& c) :
    m(b.size()), n(c.size()), N(n + 1), B(m), D(m + 2, vector<ld>(n + 2)) {
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) D[i][j] = A[i][j];}
        for (int i = 0; i < m; i++) { 
            B[i] = n + i; D[i][n] = -1; D[i][n + 1] = b[i];}
        for (int j = 0; j < n; j++) { N[j] = j; D[m][j] = -c[j]; }
        N[n] = -1; D[m + 1][n] = 1;
    }
    void Pivot(int r, int s) {
        ld inv = 1.0 / D[r][s];
        for (int i = 0; i < m + 2; i++) if (i != r)
            for (int j = 0; j < n + 2; j++) if (j != s)
                D[i][j] -= D[r][j] * D[i][s] * inv;
        for (int j = 0; j < n + 2; j++) if (j != s) D[r][j] *= inv;
        for (int i = 0; i < m + 2; i++) if (i != r) D[i][s] *= -inv;
        D[r][s] = inv;
        swap(B[r], N[s]);
    }
    bool Simplex(int phase) {
        int x = phase == 1 ? m + 1 : m;
        while (true) {
            int s = -1;
            for (int j = 0; j <= n; j++) {
                if (phase == 2 && N[j] == -1) continue;
                if (s==-1||D[x][j]<D[x][s]||(D[x][j]==D[x][s]&&N[j]<N[s])) s=j;
            }
            if (D[x][s] > -eps) return true;
            int r = -1;
            for (int i = 0; i < m; i++) {
                if (D[i][s] < eps) continue;
                if (r == -1 || D[i][n + 1] / D[i][s] < D[r][n + 1] / D[r][s] ||
                    ((D[i][n + 1]/D[i][s])==(D[r][n+1]/D[r][s])&&B[i]<B[r]))r=i;
            }
            if (r == -1) return false;
            Pivot(r, s);
        }
    }
    ld Solve(vector<ld>& x) {
        int r = 0;
        for (int i = 1; i < m; i++) if (D[i][n + 1] < D[r][n + 1]) r = i;
        if (D[r][n + 1] < -eps) {
            Pivot(r, n);
            if (!Simplex(1) || D[m + 1][n + 1] < -eps) return -inf;
            for (int i = 0; i < m; i++) if (B[i] == -1) {
                int s = -1;
                for (int j = 0; j <= n; j++)
                if (s==-1||D[i][j]<D[i][s]||(D[i][j]==D[i][s]&&N[j]<N[s])) s=j;
                Pivot(i, s);
            }
        }
        if (!Simplex(2)) return inf;
        x = vector<ld>(n);
        for (int i = 0; i < m; i++) if (B[i] < n) x[B[i]] = D[i][n + 1];
        return D[m][n + 1];
    }
};
 
vector<vector<ld> > lpA;
vector<ld> lpb;
 
void addC(vector<int> t, int s, int v){
    vector<ld> r(400);
    for (int a:t){
        if (s==1) r[a-1]=1;
        else r[a-1]=-1;
    }
    lpA.push_back(r);
    if (s==1) lpb.push_back(v);
    else lpb.push_back(-v);
}
 
vector<int> g[444];
int p[444];
vector<int> vs[444];
void dfs(int x, int d, int k){
    vs[d].push_back(x);
    if (d==k){
        vector<int> c;
        while (d>0){
            c.push_back(x);
            x=p[x];
            d--;
        }
        addC(c, -1, 1);
        return;
    }
    for (int nx:g[x]){
        if (nx!=p[x]){
            p[nx]=x;
            dfs(nx, d+1, k);
        }
    }
}
 
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n,k;
    cin>>n>>k;
    if (k*k>n) {
        cout<<"DA"<<endl;
        return 0;
    }
    for (int i=0;i<n-1;i++){
        int a,b;
        cin>>a>>b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    dfs(1, 0, k);
    for (int i=1;i<=k;i++){
        addC(vs[i], 1, 1);
    }
    vector<ld> lpc(400);
    for (int i=0;i<400;i++){
        lpc[i]=1;
    }
    LPSolver lp(lpA, lpb, lpc);
    vector<ld> ans;
    ld val=lp.Solve(ans);
    if (val>0){
        cout<<"DA"<<endl;
    }
    else{
        cout<<"NE"<<endl;
    }
}