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AtCoder/abc390/A_12435.cpp

@@ -0,0 +1,34 @@
+#include <bits/stdc++.h>
+#define lo long long
+#define INF INT_MAX
+#define LLM LONG_LONG_MAX
+
+using namespace std;
+const int N = 1e7 + 10;
+/*
+    toothless. #17
+    @fredcss_dev
+*/
+
+int a[N], b[N];
+
+signed main()
+{
+    for (int i = 1; i <= 5; i++) {
+        cin >> a[i];
+        b[i] = a[i];
+    }
+    if (a[1] == 1 && a[2] == 2 && a[3] == 3 && a[4] == 4 && a[5] == 5) {
+        puts("No");
+        return 0;
+    }
+    sort(b + 1, b + 6);
+    int cnt = 0, r = 0;
+    for (int i = 1; i <= 5; i++) {
+        if (a[i] != b[i]) cnt++;
+        if (a[i] != b[i] && i != 1 && a[i - 1] != b[i - 1]) r = 1;
+    }
+    if (cnt == 2 && r == 1) puts("Yes");
+    else puts("No");
+    return 0;
+}

AtCoder/abc390/B_Geometric_Sequence.cpp

@@ -0,0 +1,33 @@
+#include <bits/stdc++.h>
+#define lo long long
+#define INF INT_MAX
+#define LLM LONG_LONG_MAX
+
+using namespace std;
+const lo N = 1e7 + 10;
+/*
+    toothless. #17
+    @fredcss_dev
+*/
+
+lo n;
+lo a[N], b;
+bool flag = 0;
+
+signed main()
+{
+    cin >> n;
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+    }
+    for (int i = 3; i <= n; i++)
+    {
+        if (a[i] * a[1] != a[i - 1] * a[2])
+        {
+            puts("No");
+            return 0;
+        }
+    }
+    puts("Yes");
+    return 0;
+}

AtCoder/abc390/C_Paint_to_make_a_rectangle.cpp

@@ -0,0 +1,60 @@
+#include <bits/stdc++.h>
+#define lo long long
+#define INF INT_MAX
+#define LLM LONG_LONG_MAX
+
+using namespace std;
+const int N = 1e7 + 10;
+/*
+    toothless. #17
+    @fredcss_dev
+*/
+
+bool f(int h, int w, vector<string>& g)
+{
+    int top = h, b = -1, l = w, r = -1;
+    for (int i = 0; i < h; i++) {
+        for (int j = 0; j < w; j++) {
+            if (g[i][j] == '#') {
+                top = min(top, i);
+                b = max(b, i);
+                l = min(l, j);
+                r = max(r, j);
+            }
+        }
+    }
+    if (b == -1) return true;
+    for (int i = top; i <= b; i++) {
+        for (int j = l; j <= r; j++) {
+            if (g[i][j] == '.') return false;
+        }
+    }
+    for (int i = 0; i < h; i++) {
+        for (int j = 0; j < w; j++) {
+            if (i < top || i > b || j < l || j > r) {
+                if (g[i][j] == '#') return false;
+            }
+        }
+    }
+    return true;
+}
+
+signed main()
+{
+    int h, w;
+    cin >> h >> w;
+    if (h == 1 && w == 1) {
+        puts("Yes");
+        return 0;
+    }
+    vector<string> g(h);
+    for (int i = 0; i < h; i++) {
+        cin >> g[i];
+    }
+    if (f(h, w, g)) {
+        cout << "Yes" << endl;
+    } else {
+        cout << "No" << endl;
+    }
+    return 0;
+}

AtCoder/abc391/A_Lucky_Direction.cpp

@@ -0,0 +1,30 @@
+#include <bits/stdc++.h>
+#define lo long long
+#define INF INT_MAX
+#define LLM LONG_LONG_MAX
+
+using namespace std;
+const int N = 1e7 + 10;
+/*
+    toothless. #17
+    @fredcss_dev
+*/
+
+map<string, string> mp;
+
+string n;
+
+signed main()
+{
+    mp["N"] = "S";
+    mp["E"] = "W";
+    mp["W"] = "E";
+    mp["S"] = "N";
+    mp["NE"] = "SW";
+    mp["NW"] = "SE";
+    mp["SE"] = "NW";
+    mp["SW"] = "NE";
+    cin >> n;
+    cout << mp[n];
+    return 0;
+}

AtCoder/abc391/B_Seek_Grid.cpp

@@ -0,0 +1,48 @@
+#include <bits/stdc++.h>
+#define lo long long
+#define INF INT_MAX
+#define LLM LONG_LONG_MAX
+
+using namespace std;
+const int N = 1e7 + 10;
+/*
+    toothless. #17
+    @fredcss_dev
+*/
+
+signed main() {
+    int N, M;
+    cin >> N >> M;
+
+    vector<vector<char> > S(N, vector<char>(N));
+    vector<vector<char> > T(M, vector<char>(M));
+    for (int i = 0; i < N; ++i) {
+        for (int j = 0; j < N; ++j) {
+            cin >> S[i][j];
+        }
+    }
+    for (int i = 0; i < M; ++i) {
+        for (int j = 0; j < M; ++j) {
+            cin >> T[i][j];
+        }
+    }
+    for (int a = 0; a <= N - M; ++a) {
+        for (int b = 0; b <= N - M; ++b) {
+            bool match = true;
+            for (int i = 0; i < M; ++i) {
+                for (int j = 0; j < M; ++j) {
+                    if (S[a + i][b + j] != T[i][j]) {
+                        match = false;
+                        break;
+                    }
+                }
+                if (!match) break;
+            }
+            if (match) {
+                cout << a + 1 << " " << b + 1 << endl;
+            }
+        }
+    }
+
+    return 0;
+}

AtCoder/abc391/C_Pigeonhole_Query.cpp

@@ -0,0 +1,32 @@
+#include <iostream>
+#include <vector>
+using namespace std;
+
+int n, q, mp[10005], g[10005], cnt = 0, a, b, c;
+
+int main()
+{
+    cin >> n >> q;
+    for (int i = 0; i <= n; i++)
+    {
+        mp[i] = 1;
+        g[i] = i;
+    }
+    while (q--)
+    {
+        cin >> a;
+        if (a == 1)
+        {
+            cin >> b >> c;
+            if (mp[g[b]] == 2)
+                cnt--;
+            if (mp[c] == 1)
+                cnt++;
+            mp[g[b]]--;
+            mp[c]++;
+            g[b] = c;
+        }
+        else if (a == 2)
+            cout << cnt << endl;
+        return 0;
+    }

CodeForces/Codeforces Round 1007 (Div. 2)/A_The_Play_Never_Ends.cpp

@@ -0,0 +1,28 @@
+#include <bits/stdc++.h>
+#define lo long long
+#define INF INT_MAX
+#define LLM LONG_LONG_MAX
+#define endl "\n"
+
+using namespace std;
+const int N = 1e7 + 10;
+/*
+    toothless. #17
+    @fredcss_dev
+*/
+
+int t, k;
+
+bool wczffl_503(int k) {
+    return (k % 3 == 1);
+}
+
+signed main() {
+    cin >> t;
+    while (t--){
+        cin >> k;
+        if (wczffl_503(k)) cout << "YES" << endl;
+        else cout << "NO" << endl;
+    }
+    return 0;
+}

CodeForces/Codeforces Round 1007 (Div. 2)/B_Perfecto.cpp

@@ -0,0 +1,76 @@
+#include <bits/stdc++.h>
+#define lo long long
+#define INF INT_MAX
+#define LLM LONG_LONG_MAX
+#define endl "\n"
+
+using namespace std;
+const int N = 1e7 + 10;
+/*
+    toothless. #17
+    @fredcss_dev
+*/
+
+bool f(lo x) {
+    if (x < 0) return false;
+    lo root = sqrtl(x);
+    return root * root == x;
+}
+
+void wczffl_503() {
+    int n;
+    cin >> n;
+    lo total = 1LL * n * (n + 1) / 2;
+    if (f(total)) {
+        cout << "-1\n";
+        return;
+    }
+    vector<lo> s(n + 1);
+    for (int i = 1; i <= n; ++i) {
+        s[i] = (2LL * n - i + 1) * i / 2;
+    }
+    vector<bool> jhd(n + 1, false);
+    for (int i = 1; i <= n - 1; ++i) {
+        if (f(s[i])) {
+            jhd[i] = true;
+        }
+    }
+    bool bad = false;
+    for (int i = 1; i <= n; ++i) {
+        lo now = s[i];
+        if (i <= n - 1 && jhd[i]) {
+            now--;
+        }
+        if (f(now)) {
+            bad = true;
+            break;
+        }
+    }
+    if (bad) {
+        cout << "-1\n";
+        return;
+    }
+    vector<int> p(n);
+    for (int i = 0; i < n; ++i) {
+        p[i] = n - i;
+    }
+    for (int i = 1; i <= n - 1; ++i) {
+        if (jhd[i]) {
+            swap(p[i - 1], p[i]);
+        }
+    }
+    for (int x : p) {
+        cout << x << ' ';
+    }
+    cout << '\n';
+}
+
+signed main()
+{
+    int t;
+    cin >> t;
+    while (t--) {
+        wczffl_503();
+    }
+    return 0;
+}

CodeForces/Codeforces Round 1007 (Div. 2)/C_Trapmigiano_Reggiano.cpp

@@ -0,0 +1,64 @@
+#include <bits/stdc++.h>
+#define lo long long
+#define INF INT_MAX
+#define LLM LONG_LONG_MAX
+#define endl "\n"
+
+using namespace std;
+const int N = 1e7 + 10;
+/*
+    toothless. #17
+    @fredcss_dev
+*/
+
+vector<int> f(int root, const vector<vector<int>>& adj) {
+    vector<int> post_order;
+    stack<tuple<int, int, bool>> s;
+    s.push({root, -1, false});
+    
+    while (!s.empty()) {
+        auto [node, parent, visited] = s.top();
+        s.pop();
+        if (visited) {
+            post_order.push_back(node);
+        } else {
+            s.push({node, parent, true});
+            for (int neighbor : adj[node]) {
+                if (neighbor != parent) {
+                    s.push({neighbor, node, false});
+                }
+            }
+        }
+    }
+    return post_order;
+}
+
+void wczffl_503() {
+    int t;
+    cin >> t;
+    while (t--) {
+        int n, st, en;
+        cin >> n >> st >> en;
+        vector<vector<int>> adj(n + 1);
+        for (int i = 0; i < n - 1; ++i) {
+            int u, v;
+            cin >> u >> v;
+            adj[u].push_back(v);
+            adj[v].push_back(u);
+        }
+        
+        vector<int> p = f(en, adj);
+        if (p.back() != en) {
+            p.push_back(en);
+        }
+        for (int x : p) {
+            cout << x << ' ';
+        }
+        cout << '\n';
+    }
+}
+
+int main() {
+    wczffl_503();
+    return 0;
+}

Luogu/P_1015_NOIP_1999_普及组_回文数.cpp

@@ -0,0 +1,58 @@
+#include <bits/stdc++.h>
+#define int long long
+#define endl "\n"
+#define IMX LONG_LONG_MAX
+#define IMN LONG_LONG_MIN
+#define debug$ if (dev)
+using namespace std;
+
+/* toothless. #17 */
+
+const int N = 1e7 + 10;
+const int M = 2e3 + 5;
+const bool dev = false;
+
+char s[M];
+int a[M], top;
+bool check()
+{
+    int t = top / 2;
+    for (int i = 0; i <= t; ++i)
+        if (a[i] != a[top - i])
+            return true;
+    return false;
+}
+
+signed main()
+{
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    cout.tie(0);
+    int n, step = 0;
+    cin >> n >> s;
+    top = strlen(s) - 1;
+    for (int i = 0; i <= top; ++i)
+        if (s[i] >= '0' && s[i] <= '9')
+            a[top - i] = s[i] - '0';
+        else
+            a[top - i] = s[i] - 55;
+    while (check()) {
+        if (step > 30) {
+            cout << "Impossible!";
+            return 0;
+        }
+        for (int i = 0; i <= top; ++i)
+            if (top - i >= i)
+                a[i] += a[top - i];
+            else
+                a[i] = a[top - i];
+        for (int i = 0; i <= top; ++i)
+            if (a[i] >= n)
+                a[i + 1]++, a[i] -= n;
+        if (a[top + 1])
+            top++;
+        step++;
+    }
+    cout << "STEP=" << step;
+    return 0;
+}

Luogu/P_10446_64_位整数乘法.cpp

@@ -0,0 +1,34 @@
+#include <bits/stdc++.h>
+#define lo long long
+#define IMX LONG_LONG_MAX
+#define IMN LONG_LONG_MIN
+
+using namespace std;
+const int N = 1e7 + 10;
+/*
+    toothless. #17
+    @fredcss_dev
+*/
+
+lo qpow(lo a, lo b, lo p) {
+    lo result = 0;
+    while (b) {
+        if (b & 1) {
+            result += a;
+            result %= p;
+        }
+        b >>= 1;
+        a += a;
+        a %= p;
+    }
+    return result;
+}
+
+lo a, b, p; 
+
+signed main()
+{
+	cin >> a >> b >> p;
+	cout << qpow(a, b, p);
+    return 0;
+}

Luogu/P_1060_NOIP_2006_普及组_开心的金明.cpp

@@ -0,0 +1,27 @@
+#include <bits/stdc++.h>
+#define lo long long
+#define IMX LONG_LONG_MAX
+#define IMN LONG_LONG_MIN
+
+using namespace std;
+const int N = 1e7 + 10;
+/*
+    toothless. #17
+    @fredcss_dev
+    <2025/1/21>
+*/
+
+int m, n, d[N], w, v;
+
+signed main()
+{
+	cin >> m >> n;
+    for(int i = 1; i <= n; i++) {
+        cin >> v >> w;
+        for(int j = m; j >= v; j--){
+            d[j] = max(d[j], d[j - v] + w * v);
+        }
+    }
+    printf("%d",d[m]);
+    return 0;
+}

Luogu/P_1135_奇怪的电梯.cpp

@@ -0,0 +1,49 @@
+#include <bits/stdc++.h>
+#define int long long
+#define endl "\n"
+#define IMX LONG_LONG_MAX
+#define IMN LONG_LONG_MIN
+#define debug$ if(dev)
+using namespace std;
+
+/* toothless. #17 */
+
+const int N = 1e7 + 10;
+const int M = 2e3 + 5;
+const bool dev = false;
+
+int n, k;
+int a[N];
+int ans=0;
+
+bool isPrime(int x)
+{
+    if (x == 1)
+        return false;
+    for (int i = 2; i * i <= x; i++)
+        if (x % i == 0)
+            return false;
+    return true;
+}
+
+void dfs(int x, int sum, int cnt)
+{
+    if (x == k) {
+        if (isPrime(sum))
+            ans++;
+        return;
+    }
+    for (int i = cnt; i < n; i++) {
+        dfs(x + 1, sum + a[i], i + 1);
+    }
+}
+
+signed main()
+{
+    cin >> n;
+    for (int i = 1; i <= n; i++)
+        cin >> a[i];
+    dfs(0, 0, 0);
+    cout << ans << endl;
+    return 0;
+}`

README.md

@@ -10,6 +10,7 @@ Here's my personal solutions to algorithm problems.
 
 | Name | Link | Account
 | :---: | :---: | :---: |
+| AtCoder | atcoder.jp | [wczffL_4ever](https://atcoder.jp/users/wczffL_4ever) |
 | Codeforces | codeforces.com | [Fengyi_Chen](https://codeforces.com/profile/Fengyi_Chen) |
 | FZOI | 内部 OJ | 内部 OJ |
 | Luogu | luogu.com.cn | [BunDragon126](https://www.luogu.com.cn/user/927203) |