P1179 [NOIP2010 普及组] 数字统计

R63283669

Luogu/P1179/P1179.cpp

@@ -0,0 +1,23 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int l, r, ans;
+
+int cnt2(int x) {
+    int res = 0;
+    while (x) {
+        res += x % 10 == 2;
+        x /= 10;
+    }
+    return res;
+}
+
+int main() {
+    cin >> l >> r;
+    for (int i = l; i <= r; i++) {
+        ans += cnt2(i);
+    }
+    cout << ans << endl;
+    return 0;
+}