atcoder/abc192D

Author: xirc

atcoder/abc192/D/main.cpp

@@ -0,0 +1,62 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+string X;
+ll M;
+
+bool pass(ll n) {
+    if (n == 0) return true;
+    ll v = 0;
+    for (int i = 0; i < X.size(); ++i) {
+        int x = X[i] - '0';
+        if (v > M / n) return false;
+        v *= n;
+        if (v > M - x) return false;
+        v += x;
+    }
+    return true;
+}
+
+int minbase() {
+    int n = 0;
+    for (int i = 0; i < X.size(); ++i) {
+        n = max(n, X[i] - '0');
+    }
+    return n + 1;
+}
+
+ll maxbase() {
+    ll ok = 0, ng = 2e18;
+    while (abs(ok - ng) > 1) {
+        auto m = (ok + ng) / 2;
+        if (pass(m)) {
+            ok = m;
+        } else {
+            ng = m;
+        }
+    }
+    return ok;
+}
+
+ll solve() {
+    if (X.size() == 1) {
+        return (X[0]-'0' <= M) ? 1 : 0;
+    }
+    ll mini = minbase();
+    ll maxi = maxbase();
+    if (maxi < mini) return 0;
+    return maxi - mini + 1;
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    cin >> X >> M;
+    cout << solve() << endl;
+
+    return 0;
+}