4027: [HEOI2015]兔子与樱花 贪心

别人家的省选T_T
直接sb贪心就好了。。每次选最小的。。

#include<iostream>#include<cstdio>#include<vector>#include<algorithm>#define N 2000005using namespace std;int n,m,ans,c[N];vector<int> a[N];inline int read(){    int a=0,f=1; char c=getchar();    while (c<'0'||c>'9') {if (c=='-') f=-1; c=getchar();}    while (c>='0'&&c<='9') {a=a*10+c-'0'; c=getchar();}    return a*f;}inline bool cmp(int a,int b){    return c[a]<c[b];}void dfs(int x){    c[x]+=a[x].size();    for (int i=0;i<a[x].size();i++) dfs(a[x][i]);    sort(a[x].begin(),a[x].end(),cmp);    for (int i=0;i<a[x].size();i++)        if (c[x]+c[a[x][i]]-1<=m)            c[x]+=c[a[x][i]]-1,ans++;        else break;}int main(){    n=read(); m=read();    for (int i=0;i<n;i++) c[i]=read();    for (int i=0;i<n;i++)    {        int x=read();        while (x--)        {            int y=read();            a[i].push_back(y);        }    }    dfs(0);    cout << ans;    return 0;}