Merge pull request #396 from xirc/atcoder/abc023

AtCoder/ABC023

Author: xirc

atcoder/abc023/A/main.cpp

@@ -0,0 +1,22 @@
+#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 X;
+    cin >> X;
+
+    int sum = 0;
+    while (X > 0) {
+        sum += X % 10;
+        X /= 10;
+    }
+    cout << sum << endl;
+
+    return 0;
+}

atcoder/abc023/B/main.cpp

@@ -0,0 +1,41 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+int solve(int const N, string const& S) {
+    if (N % 2 == 0) {
+        return -1;
+    }
+    int const M = N / 2;
+    if (S[M] != 'b') return -1;
+
+    int l = M - 1, r = M + 1;
+    int n = 1;
+    vector<string> pairs = {
+        "bb",
+        "ac",
+        "ca",
+    };
+    while (l >= 0 && r < N) {
+        if (pairs[n%3][0] != S[l]) return -1;
+        if (pairs[n%3][1] != S[r]) return -1;
+        ++n;
+        --l;
+        ++r;
+    }
+    return n-1;
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    int N;
+    string S;
+    cin >> N >> S;
+    cout << solve(N, S) << endl;
+
+    return 0;
+}

atcoder/abc023/C/main.cpp

@@ -0,0 +1,60 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+int R, C, K;
+int N;
+vector<int> rs, cs;
+
+ll solve() {
+    vector<vector<int>> G(R, vector<int>());
+    vector<int> candies_by_row(R, 0);
+    vector<int> candies_by_col(C, 0);
+    for (int i = 0; i < N; ++i) {
+        ++candies_by_row[rs[i]];
+        ++candies_by_col[cs[i]];
+        G[rs[i]].push_back(cs[i]);
+    }
+
+    map<int,int> cols_by_candies;
+    for (int c = 0; c < C; ++c) {
+        ++cols_by_candies[candies_by_col[c]];
+    }
+
+    ll cells = 0;
+    for (int r = 0; r < R; ++r) {
+        for (auto c : G[r]) {
+            int candies = candies_by_col[c];
+            --cols_by_candies[candies];
+            ++cols_by_candies[candies-1];
+        }
+
+        cells += cols_by_candies[K - candies_by_row[r]];
+
+        for (auto c : G[r]) {
+            int candies = candies_by_col[c];
+            ++cols_by_candies[candies];
+            --cols_by_candies[candies-1];
+        }
+    }
+    return cells;
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    cin >> R >> C >> K;
+    cin >> N;
+    rs.assign(N, 0);
+    cs.assign(N, 0);
+    for (int i = 0; i < N; i++) {
+        cin >> rs[i] >> cs[i];
+        --rs[i], --cs[i];
+    }
+    cout << solve() << endl;
+
+    return 0;
+}

atcoder/abc023/D/main.cpp

@@ -0,0 +1,56 @@
+#include <bits/stdc++.h>
+
+inline int64_t binary_search(
+    std::function<bool(int64_t)> const& predicate,
+    int64_t ng,
+    int64_t ok
+) {
+    assert(!predicate(ng) && predicate(ok));
+    while (abs(ok - ng) > 1) {
+        auto m = (ok + ng) / 2;
+        if (predicate(m)) ok = m;
+        else ng = m;
+    }
+    return ok;
+}
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+int N;
+vector<ll> H, S;
+
+vector<ll> ts;
+bool pass(ll const X) {
+    for (int i = 0; i < N; ++i) {
+        if (X - H[i] < 0) return false;
+        ts[i] = (X - H[i]) / S[i];
+    }
+    sort(ts.begin(), ts.end());
+    for (int i = 0; i < N; ++i) {
+        if (i > ts[i]) return false;
+    }
+    return true;
+}
+
+ll solve() {
+    ts.assign(N, 0);
+    ll ng = 0, ok = numeric_limits<ll>::max() / 10;
+    return binary_search(pass, ng, ok);
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    cin >> N;
+    H.assign(N, 0);
+    S.assign(N, 0);
+    for (int i = 0; i < N; i++) {
+        cin >> H[i] >> S[i];
+    }
+    cout << solve() << endl;
+
+    return 0;
+}

lib/cpalgo/util/README.md

@@ -25,6 +25,7 @@ We can use this technique in many problems. It's a pretty powerful technique.
 ### Challenges
 - [食塩水](https://atcoder.jp/contests/abc034/tasks/abc034_d)
 - [Widespread](https://atcoder.jp/contests/abc063/tasks/arc075_b)
+- [射撃王](https://atcoder.jp/contests/abc023/tasks/abc023_d)
 
 
 ## Dice