Codeforces round #260 (Div. 1)

The Junior goal is to yellow codeforces!

Start with div1 and do the first three questions each time.

A

A simple DP.

#include<iostream>#include<algorithm>#include<cstring>#include<cstdio>#include<cstdlib>#include<string>#include<cmath>#include<vector>#define LL long long#define MAXN 100005using namespace std;LL vis[100005];LL dp[1000005];int main(){    int n;    scanf("%d",&n);    int maxi=0;    for(int i=0; i<n; ++i)    {        int a;        scanf("%d",&a);        vis[a]+=a;        maxi=max(maxi,a);    }    for(int i=1; i<=maxi; ++i)        if(i-2>=0)            dp[i]=max(dp[i-1],dp[i-2]+vis[i]);        else            dp[i]=vis[i];    printf("%I64d\n",dp[maxi]);    return 0;}

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B

Tire + dp + game

Win [I] indicates whether there is a possibility of victory in the first hand at the I node, and lost [I] indicates whether there is a possibility of failure in the first hand at the current I node.

In this way, you can determine whether the first hand has the possibility of winning or failing, and then perform a simple game.

#include<iostream>#include<algorithm>#include<cstdio>#include<cstring>#include<vector>using namespace std;int n,K;struct Tire{    int ch[100005][26];    bool win[100005],lost[100005];    int sz;    int newnode()    {        memset(ch[sz],0,sizeof(ch[sz]));        win[sz]=lost[sz]=0;        return sz++;    }    void init()    {        sz=0;        newnode();    }    int getX(char c)    {        return c-‘a‘;    }    void insert(char *word)    {        int now=0;        for(int i=0; word[i]; ++i)        {            int x=getX(word[i]);            if(ch[now][x]==0)                ch[now][x]=newnode();            now=ch[now][x];        }    }    bool getWin(int now)    {        win[now]=false;        bool noChild=true;        for(int i=0; i<26; ++i)        {            if(ch[now][i])            {                noChild=false;                win[now]|=(!getWin(ch[now][i]));            }        }        if(noChild) return win[now]=false;        return win[now];    }    bool getLost(int now)    {        lost[now]=false;        bool noChild=true;        for(int i=0; i<26; ++i)        {            if(ch[now][i])            {                noChild=false;                lost[now]|=(!getLost(ch[now][i]));            }        }        if(noChild) return lost[now]=true;        return lost[now];    }};char word[100005];Tire tree;int main(){    scanf("%d%d",&n,&K);    tree.init();    for(int i=1; i<=n; ++i)    {        scanf("%s",word);        tree.insert(word);    }    bool firstWin=false,firstLost=false;    firstWin=tree.getWin(0);    firstLost=tree.getLost(0);    if(!firstWin) puts("Second");    else    {        if(firstLost) puts("First");        else        {            if(K&1) puts("First");            else puts("Second");        }    }    return 0;}

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Codeforces round #260 (Div. 1)