循环某个范围的数, 计算平方, 根据第二个参数数字, 计算该数字出现几次nbDig

Author: uuk020

nbDig/nbDig.php

@@ -0,0 +1,23 @@
+<?php
+/*
+ * 循环某个范围的数,算出每个数的平方,根据第二个参数中数字,看该数字在得出结果出现几次
+*/
+function nbDig($n, $d)
+{
+    // your code
+    $str = '';
+    for ($i = 0; $i <= $n; $i++) {
+        // 计算数字后拼接字符串
+        $str .= (string)pow($i, 2);
+    }
+    // substr_count计算字串出现的次数
+    $count = substr_count($str, (string)$d);
+    return $count;
+}
+/**
+ * Take an integer n (n >= 0) and a digit d (0 <= d <= 9) as an integer. Square all numbers k (0 <= k <= n) between 0 and n.
+ * Count the numbers of digits d used in the writing of all the k**2. Call nb_dig (or nbDig or ...)
+ * the function taking n and d as parameters and returning this count.
+ * n = 10, d = 1, the k*k are 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100
+ * We are using the digit 1 in 1, 16, 81, 100. The total count is then 4.
+ */