'commit'

TangDou/LuoGuBook/20_1_8.cpp

@@ -0,0 +1,19 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+int cnt;
+
+int main() {
+    for (int i = 10000; i <= 19999; i++) {
+        int n = i;
+        while (n) {
+            if (n % 10 == 4) {
+                cnt++;
+                break;
+            }
+            n /= 10;
+        }
+    }
+    cout << cnt << endl;
+    return 0;
+}