2019ICPC上海站

https://ac.nowcoder.com/acm/contest/4370

 

B题

判断是不是前缀编码T组样例，N个字符串，判断有没有一个是另一个的前缀

 

Trie

标记这个节点的编号是否出现过两次

注意，一定要有ed,比如说第二组测试样例，如果没有ed,5,59此时5已经走过了

#include <bits/stdc++.h>
using namespace std;
const int maxn = 10005 * 10;
string str;
int t,n;
int flag;
int trie[maxn][26],id = 1,vis[maxn],ed[maxn];
void insert(string s) {
    int p = 1;
    for(int i = 0; i < s.size(); i++) {
        int ch = s[i] - '0';
        if (trie[p][ch]== -1)
            trie[p][ch] = ++id;
        p = trie[p][ch];
        if(ed[p])
            flag = 0;
        vis[p]++;
    }
    if(vis[p] > 1)
        flag = 0;
    ed[p]++;

}
int main(){
    //freopen("in","r",stdin);
    ios::sync_with_stdio(0);
    cin >> t;
    for(int i = 1; i <= t;i++){
        cout << "Case #" << i << ": ";
        cin >> n;
        flag = 1;
        memset(vis,0, sizeof(vis));
        memset(ed,0, sizeof(ed));
        memset(trie,-1, sizeof(trie));
        id = 1;
        for(int j = 1; j <= n; j++) {
            cin >> str;
            insert(str);
        }
        if(flag)
            cout << "Yes" << endl;
        else cout << "No" << endl;
    }
    return 0;
}

 

 

 

 

K Color Graph

 

 

#include <bits/stdc++.h>

using namespace std;
int t, n, m;
int u[205], v[205];
int vis[20];
int ans;

void dfs(int x) {
    if (x == n) {
        int cnt = 0;
        for (int i = 1; i <= m; i++)
            cnt += (vis[u[i]] ^ vis[v[i]]);
        ans = max(ans, cnt);
        return;
    }

    vis[x] = 1;
    dfs(x + 1);
    vis[x] = 0;

    dfs(x + 1);
}

int main() {
    //freopen("in", "r", stdin);
    ios::sync_with_stdio(0);
    cin >> t;
    for (int j = 1; j <= t; j++) {
        cin >> n >> m;
        ans = 0;
        for (int i = 1; i <= m; i++)
            cin >> u[i] >> v[i];
        dfs(1);
        cout << "Case #" << j << ": " << ans << endl;
    }
    return 0;
}