從今天開始刷CF，從round400 開始，div1,2,3都要做，並記錄自己的刷題進度，限時刷題（像比賽一樣）+ 補題， 以此記錄我的CF變紅之路。 A

#include <bits/stdc++.h>
using namespace std;

typedef pair<string, string> Pair;

int main()
{
    //freopen("input.txt", "r", stdin);
    string a, b;
    cin >> a >> b;
    cout << a << " "
 
 << b << endl;
    Pair p(a, b);
    int n;
    scanf("%d", &n);
    while(n--) {
        cin >> a >> b;
        if(a==p.first) {
            p.first = b;
        }
        else if(a == p.second) {
            p.second = b;
        }
        else if(b == p.first) {
            p.first = a;
        }
        else
 
 if(b == p.second) {
            p.second = a;
        }
        cout << p.first << " " << p.second << endl;
    }
    return 0;
}

B

#include <bits/stdc++.h>
using namespace std;

bool isprim(int n) {
    for(int i = 2; i <= sqrt(n); i++) {
        if(n % i == 0) return
 
 false;
    }
    return true;
}

int main()
{
    //freopen("input.txt", "r", stdin);
    int n;
    cin >> n;
    if(n <= 2) {
        cout << 1 << endl;
    }
    else cout << 2 << endl;
    int fir = 1;
    for(int i = 2; i <= n + 1; i++) {
        if(fir) {
            if (isprim(i)) {
                cout << 1 << endl;
            }
            else {
                cout << 2 << endl;
            }
            fir = 0;
        }
        else {
            if (isprim(i)) {
                cout << 1 << endl;
            }
            else {
                cout << 2 << endl;
            }
            fir = 0;
        }
    }
    return 0;
}

C

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = (int)1e5 + 10;
const ll inf = (ll)1e14;
ll sum[maxn];
map<ll, ll> mp;
set<ll> st;

int main() {
    //freopen("input.txt", "r", stdin);
    ll n, k;
    while(cin >> n >> k) {
        mp.clear();
        st.clear();
        sum[0] = 0;
        for(int i = 1; i <= n; i++) {
            scanf("%lld", &sum[i]);
            sum[i] += sum[i-1];
        }
        ll tmp = 1;
        st.insert(tmp);
        for(int i = 0; i <= 64; i++) {
            tmp *= k;
            if(tmp > inf) break;
            st.insert(tmp);
        }
        ll ans = 0;
        for(int i = 0; i <= n; i++) {
            for(set<ll>::iterator it = st.begin(); it != st.end(); it++) {
                ans += mp[sum[i] - *it];
            }
            mp[sum[i]]++;
        }
        cout << ans << endl;
    }
    return 0;
}

還有幾道題未補先佔個坑，剛開始做CF感覺題目思維量很大，需要大量練習才行。加油～