Merge pull request #454 from xirc/atcoder/abc143

AtCoder/ABC143

Author: xirc

atcoder/abc143/A/main.cpp

@@ -0,0 +1,17 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    int A, B;
+    cin >> A >> B;
+    int C = max(0, A - 2 * B);
+    cout << C << endl;
+
+    return 0;
+}

atcoder/abc143/B/main.cpp

@@ -0,0 +1,28 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    int N;
+    vector<int> ds;
+
+    cin >> N;
+    ds.assign(N, 0);
+    for (int i = 0; i < N; ++i) {
+        cin >> ds[i];
+    }
+    int ans = 0;
+    for (int i = 0; i < N; ++i) {
+        for (int j = i + 1; j < N; ++j) {
+            ans += ds[i] * ds[j];
+        }
+    }
+    cout << ans << endl;
+
+    return 0;
+}

atcoder/abc143/C/main.cpp

@@ -0,0 +1,23 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    int N;
+    string S;
+    cin >> N >> S;
+    deque<char> cs;
+    for (auto c : S) {
+        if (cs.empty() || cs.back() != c) {
+            cs.push_back(c);
+        }
+    }
+    cout << cs.size() << endl;
+
+    return 0;
+}

atcoder/abc143/D/main.cpp

@@ -0,0 +1,48 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+int N;
+vector<int> ls;
+
+ll solve() {
+    int const LMAX = 2000;
+    vector<int> acc(LMAX+1, 0);
+    for (int i = 0; i < N; ++i) {
+        acc[ls[i]]++;
+    }
+    for (int i = 1; i < LMAX+1; ++i) {
+        acc[i] += acc[i-1];
+    }
+
+    ll ans = 0;
+    for (int i = 0; i < N; ++i) {
+        for (int j = 0; j < N; ++j) {
+            if (i == j) continue;
+            int a = ls[i], b = ls[j];
+            // [cmin,cmax]
+            int cmin = abs(a - b) + 1;
+            int cmax = a + b -1;
+            auto m = acc[cmax];
+            m -= acc[cmin-1];
+            if (a >= cmin && a <= cmax) --m;
+            if (b >= cmin && b <= cmax) --m;
+            ans += m;
+        }
+    }
+    return ans / 6;
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    cin >> N;
+    ls.assign(N, 0);
+    for (auto &l : ls) cin >> l;
+    cout << solve() << endl;
+
+    return 0;
+}

atcoder/abc143/E/main.cpp

@@ -0,0 +1,69 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+const ll inf = 1e16;
+int N, L;
+vector<vector<ll>> G;
+
+void reduce() {
+    // Floyd Warshall
+    for (int k = 0; k < N; ++k) {
+        for (int i = 0; i < N; ++i) {
+            for (int j = 0; j < N; ++j) {
+                G[i][j] = min(G[i][j], G[i][k] + G[k][j]);
+            }
+        }
+    }
+}
+
+void build() {
+    for (int i = 0; i < N; ++i) {
+        G[i][i] = 0;
+    }
+    reduce();
+    for (int i = 0; i < N; ++i) {
+        for (int j = 0; j < N; ++j) {
+            if (i == j) G[i][j] = 0;
+            else if (G[i][j] <= L) G[i][j] = 1;
+            else G[i][j] = inf;
+        }
+    }
+    reduce();
+}
+
+int query(int u, int v) {
+    if (G[u][v] == inf)
+        return -1;
+    return G[u][v] - 1;
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    int M;
+    cin >> N >> M >> L;
+    G.assign(N, vector<ll>(N, inf));
+    for (int i = 0; i < M; ++i) {
+        int a, b, c;
+        cin >> a >> b >> c;
+        --a, --b;
+        G[a][b] = c;
+        G[b][a] = c;
+    }
+    build();
+
+    int Q;
+    cin >> Q;
+    for (int i = 0; i < Q; ++i) {
+        int s, t;
+        cin >> s >> t;
+        --s, --t;
+        cout << query(s, t) << endl;
+    }
+
+    return 0;
+}

lib/cpalgo/graph/README.md

@@ -56,7 +56,7 @@ We can find all articulation points of a given graph in `O(V + E)`.
 ### Challenges
 - [正直者の高橋くん - AtCoder ABC021C](https://atcoder.jp/contests/abc021/tasks/abc021_c)
 - [Blue Bird - AtCoder ABC022C](https://atcoder.jp/contests/abc022/tasks/abc022_c)
-
+- [Travel by Car - AtCoder ABC143E](https://atcoder.jp/contests/abc143/tasks/abc143_e)
 
 ## Bipartite