1748 solved!

Author: rainBuildingTree

Solved Archive/1748_Write_Numbers_In_Succession/a.exe

@@ -0,0 +1,12 @@
+#include <iostream>
+using namespace std;
+
+int main() {
+    int a = 99999;
+    a /= 10;
+    a /= 10;
+    a /= 10;
+    a /= 10;
+    cout << a << endl;
+    return 0;
+}

Solved Archive/1748_Write_Numbers_In_Succession/test.cpp

@@ -0,0 +1,36 @@
+#include <iostream>
+using namespace std;
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    // 1 <= N <= 100,000,000 = 10^8
+    int N;
+    cin >> N;
+
+    int size = 1;
+    for (; size < 100000001; size = size * 10)
+        if ((N / size) < 10)
+            break;
+
+    int index = 0;
+    int cp_size = size;
+    while (cp_size > 9) {
+        index++;
+        cp_size /= 10;
+    }
+
+    //cout << "[DEBUG] size = " << size << "\t index = " << index << '\n';    
+
+    int result = (index + 1) * (N - size + 1);
+    while (index > 0) {
+        result += index * (size / 10 * 9);
+        size /= 10;
+        index--;
+    }
+
+    cout << result << '\n';
+
+    return 0;
+}