'commit'

TangDou/LuoGuBook/P1591.cpp

@@ -0,0 +1,37 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+const int N = 1e6 + 10;
+int a[N];
+
+void mul(int a[], int b, int &len) {
+    int t = 0;
+    for (int i = 1; i <= len; i++) {
+        t += a[i] * b;
+        a[i] = t % 10;
+        t /= 10;
+    }
+    while (t) {
+        a[++len] = t % 10;
+        t /= 10;
+    }
+    //去前导0
+    while (len > 1 && !a[len]) len--;
+}
+
+int main() {
+    int T;
+    cin >> T;
+    while (T--) {
+        int n, x;
+        scanf("%d %d", &n, &x);
+        int al = 0, cnt = 0;
+        a[++al] = 1;
+        for (int i = 2; i <= n; i++) mul(a, i, al);
+
+        for (int i = 1; i <= al; i++)
+            if (a[i] == x) cnt++;
+        printf("%d\n", cnt);
+    }
+    return 0;
+}