top 1034

Author: tiny656

PAT (Top Level) Practice/1134_Number Game (35).cpp

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+#include <iostream>
+#include <queue>
+#include <cstring>
+using namespace std;
+const int LIMIT = 120000;
+const int OFFSET = 120000;
+
+// BFS to find the minimum steps to reach from A to B using operations +1, -1, and *N
+int minSteps(int A, int B, int N) {
+    bool visited[LIMIT + OFFSET + 1] = {false};
+    if (A == B) return 0;
+
+    queue<pair<int, int>> q;  // (value, steps)
+    q.push({A, 0});
+    visited[A + OFFSET] = true;
+
+    while (!q.empty()) {
+        auto [curr, steps] = q.front();
+        q.pop();
+
+        if (curr == B) return steps;
+
+        if (curr < LIMIT && !visited[curr + 1 + OFFSET]) {
+            visited[curr + OFFSET] = true;
+            q.push({curr + 1, steps + 1});
+        }
+
+        if (curr > -LIMIT && !visited[curr - 1 + OFFSET]) {
+            visited[curr - 1 + OFFSET] = true;
+            q.push({curr - 1, steps + 1});
+        }
+
+        int mult = curr * N;
+        if (mult >= -LIMIT && mult <= LIMIT && !visited[mult + OFFSET]) {
+            visited[mult + OFFSET] = true;
+            q.push({mult, steps + 1});
+        }
+    }
+
+    return -1;
+}
+
+int main() {
+    ios::sync_with_stdio(false);
+    int K;
+    cin >> K;
+
+    int A, B, N;
+    for (int i = 0; i < K; i++) {
+        cin >> A >> B >> N;
+        cout << minSteps(A, B, N) << endl;
+    }
+
+    return 0;
+}