update

src/7/31/P4316.cpp

@@ -0,0 +1,52 @@
+#include <cstdio>
+#include <deque>
+#include <iostream>
+#include <istream>
+#include <ranges>
+#include <tuple>
+#include <vector>
+using ll = long long;
+
+ll n,m;
+std::vector<std::vector<std::tuple<ll,ll>>> g;
+std::vector<ll> in,out;
+std::vector<double> dp;
+
+int main(){
+    std::iostream::sync_with_stdio(false);
+    std::cin.tie(nullptr);
+    std::cin>>n>>m;
+    g.resize(n+1);
+    in.resize(n+1);
+    out.resize(n+1);
+    for(ll i=1;i<=m;i++){
+        ll u,v,w;
+        std::cin>>u>>v>>w;
+        in[v]++;
+        out[u]++;
+        g[u].emplace_back(v,w);
+    }
+    std::vector<ll> sorted;
+    std::deque<ll> q;
+    for(ll i=1;i<=n;i++){
+        if(!in[i]){
+            q.push_back(i);
+        }
+    }
+    while(q.size()){
+        ll top = q.front();
+        q.pop_front();
+        sorted.push_back(top);
+        for(auto [v,w]:g[top]){
+            if(!--in[v])q.push_back(v);
+        }
+    }
+    dp.resize(n+1);
+    for(ll u:std::views::reverse(sorted)){
+        if(u==n)continue;
+        for(auto[v,w]:g[u]){
+            dp[u]+=(dp[v]+w)/out[u];
+        }
+    }
+    printf("%.2lf\n",dp[1]);
+}

src/7/31/U136947d.cpp

@@ -0,0 +1,92 @@
+#include <iostream>
+#include <vector>
+#include <cstring>
+#include <algorithm>
+using namespace std;
+
+const int MOD = 1000000007;
+const int ALPHABET_SIZE = 27; // 26 letters + '_'
+
+int char2idx(char c) {
+    if (c == '_') 
+        return 26;
+    return c - 'a';
+}
+
+int main() {
+    int n, k;
+    string s;
+    cin >> n >> k;
+    cin >> s;
+
+    vector<bool> inS(ALPHABET_SIZE, false);
+    for (char c : s) {
+        int idx = char2idx(c);
+        inS[idx] = true;
+    }
+
+    vector<long long> f(n + 1, 0);
+    vector<long long> F(n + 1, 0);
+    vector<vector<long long>> G(ALPHABET_SIZE, vector<long long>(n + 1, 0));
+    vector<vector<long long>> dp(n + 1, vector<long long>(ALPHABET_SIZE, 0));
+
+    vector<int> last_occurrence(ALPHABET_SIZE, -1);
+
+    f[0] = 1;
+    F[0] = 1;
+    for (int c = 0; c < ALPHABET_SIZE; ++c) {
+        dp[0][c] = 0;
+        G[c][0] = 0;
+    }
+
+    for (int i = 1; i <= n; ++i) {
+        int L = max(0, i - k);
+        int R = i - 1;
+        char current_char = s[i - 1];
+        int current_idx = char2idx(current_char);
+
+        for (int c = 0; c < ALPHABET_SIZE; ++c) {
+            if (!inS[c]) {
+                dp[i][c] = 0;
+                continue;
+            }
+
+            int Rc = -1;
+            if (c == current_idx) {
+                Rc = i - 1;
+            } else {
+                Rc = last_occurrence[c];
+            }
+
+            if (Rc < L) {
+                dp[i][c] = 0;
+            } else {
+                long long part1 = F[Rc] - (L - 1 >= 0 ? F[L - 1] : 0);
+                long long part2 = G[c][Rc] - (L - 1 >= 0 ? G[c][L - 1] : 0);
+                dp[i][c] = (part1 - part2) % MOD;
+                if (dp[i][c] < 0) dp[i][c] += MOD;
+            }
+        }
+
+        f[i] = 0;
+        for (int c = 0; c < ALPHABET_SIZE; ++c) {
+            if (inS[c]) {
+                f[i] = (f[i] + dp[i][c]) % MOD;
+            }
+        }
+
+        last_occurrence[current_idx] = i - 1;
+
+        F[i] = (F[i - 1] + f[i]) % MOD;
+        for (int c = 0; c < ALPHABET_SIZE; ++c) {
+            if (inS[c]) {
+                G[c][i] = (G[c][i - 1] + dp[i][c]) % MOD;
+            } else {
+                G[c][i] = G[c][i - 1];
+            }
+        }
+    }
+
+    cout << f[n] % MOD << endl;
+    return 0;
+}