算法导论16（贪心算法）

void recursiveActivitySelector(vector<int> s,vector<int> f,int k,int n,vector<int> &res)
{
int m=k+1;
while(m<=n&&s[m]<f[k])++m;
if(m<=n)res.push_back(m);
}

vector<int> greedyActivitySelector(vector<int> s,vector<int> f)
{
int n=s.size();
vector<int> A;
A.push_back(1);
int k=1;
for(int m=2;m<=n;++m)
{
if(s[m]>=f[k])
{
A.push_back(m);
k=m;
}
}
return A;
}

struct Node
{
char val;
int freq;
Node *left,*right;
Node(char x,int y):val(x),freq(y),left(NULL),right(NULL){}
};

bool cmp(Node *a,Node *b)
{
return a->freq<b->freq;
}

Node *Huffman(vector<Node *> C)
{
int n=C.size();
vector<Node *> Q=C;
for(int i=1;i<=n-1;++i)
{
Node *z=new Node('#',0),*x=NULL,*y=NULL;
make_heap(Q.begin(),Q.end(),cmp);
z->left=x=Q[0];
Q.erase(Q.begin());
make_heap(Q.begin(),Q.end(),cmp);
z->right=y=Q[0];
Q.erase(Q.begin());
z->freq=x->freq+y->freq;
Q.push_back(z);
}
return Q[0];
}