Waiting for the dawn

CF 14A

cin >> n >> m; 
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++){
            cin >> str[i][j];
            if (str[i][j] == '*') {
                if (i <= x1) x1 = i; 
                if (j <= x2) x2 = j;
                if (i >= y1) y1 = i;
                if (j >= y2) y2 = j;
            }
        }
    for(int i = x1; i <= y1; i++){
        for (int j = x2; j <= y2; j++)
            cout << str[i][j];
        cout << endl;
    }
    return 0;

daily codeforces

daily codeforces

daily codeforces

daily codeforces

daily codeforces

daily codeforces

daily codeforces

daily codeforces

CF 1036C

ll dp[MAXN][MAXB];
ll a[MAXN];
ll dfs(int pos,int st,bool flag){
    if(pos==-1)return 1;
    if(dp[pos][st]!=-1&&!flag)return dp[pos][st];
    int lim=flag?a[pos]:9;
    ll ans=0;
    for(int i=0;i<=lim;++i){
        if(i==0){
            ans+=dfs(pos-1,st,flag&&a[pos]==i);
        }else if(st!=3){
            ans+=dfs(pos-1,st+1,flag&&a[pos]==i);
        }
    }
    if(!flag)dp[pos][st]=ans;
    return ans;
}
ll cal(ll x){
    int len=0;
    while(x){
        a[len++]=x%10;
        x/=10;
    }
    return dfs(len-1,0,true);
}
int main(){
    memset(dp,-1,sizeof(dp));
    int T;
    cin>>T;
    while(T--){
        ll l,r;
        cin>>l>>r;
        cout<<cal(r)-cal(l-1)<<'\n';
    }
}

CF 1092F

int main(){
    int n;cin>>n;
    vector<ll>a(n+1),dp(n+1);
    for(int i=1;i<=n;++i)cin>>a[i];
    vector<vector<int>>E(n+1);
    for(int i=1;i<=n-1;++i){
        int u,v;
        cin>>u>>v;
        E[u].push_back(v);
        E[v].push_back(u);
    }
    vector<ll>s(n+1);
    function<void(int,int)>dfs1=[&](int x,int f){
        s[x]=a[x];
        dp[x]=0;
        for(int v:E[x]){
            if(v==f)continue;
            dfs1(v,x);
            s[x]+=s[v];
            dp[x]+=dp[v]+s[v];
        }
    };
    function<void(int,int,ll)>dfs2=[&](int x,int f,ll extra){
        for(int v:E[x]){
            if(v==f)continue;
            dp[v]=(extra+s[x]-s[v])+dp[x]-s[v];//the subtree node of v would be subtraceted s[v] and other nodes would be adding s[x]-s[v];
            dfs2(v,x,extra+s[x]-s[v]);
        }
    };
    dfs1(1,0);
    dfs2(1,0,0);
    ll ans=-1;
    for(int i=1;i<=n;++i){
        ans=max(ans,dp[i]);
    }
    cout<<ans<<'\n';
}