Commit aae4038

author

uuk020

committed

找规律计算 series_sum

1 parent 7930a64 commit aae4038Copy full SHA for aae4038

File tree

+36

-0

lines changed

+36

-0

lines changed

Lines changed: 36 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,36 @@`
	`1`	`+<?php`
	`2`	`+/**`
	`3`	`+ * 规律计算题`
	`4`	`+ * Your task is to write a function which returns the sum of following series upto nth term(parameter).`
	`5`	`+ * Series: 1 + 1/4 + 1/7 + 1/10 + 1/13 + 1/16 +...`
	`6`	`+ * You need to round the answer to 2 decimal places and return it as String.`
	`7`	`+ * If the given value is 0 then it should return 0.00`
	`8`	`+ * You will only be given Natural Numbers as arguments.`
	`9`	`+ */`
	`10`	`+function series_sum($n)`
	`11`	`+{`
	`12`	`+ // Your code here`
	`13`	`+ $offset = 1;`
	`14`	`+ if (!is_int($n)) {`
	`15`	`+ return '$n is not int';`
	`16`	`+ }`
	`17`	`+ if ($n === 0) {`
	`18`	`+ return 0.00;`
	`19`	`+ }`
	`20`	`+ for ($i = 0; $i < $n; $i++) {`
	`21`	`+ $sum += 1 / $offset;`
	`22`	`+ // 规律: 4 7 10..每次除于的数都是上个数+3`
	`23`	`+ $offset += 3;`
	`24`	`+ }`
	`25`	`+ return round($sum, 2);`
	`26`	`+}`
	`27`	`+`
	`28`	`+function series_sum_clever($n)`
	`29`	`+{`
	`30`	`+ $sum = 0;`
	`31`	`+ for($i=0; $i<$n; $i++) {`
	`32`	`+ //结合循环$i 计算每次要除于的数.为$i的值*3+1得出`
	`33`	`+ $sum += 1/(1+3*$i);`
	`34`	`+ }`
	`35`	`+ return round($sum,2);`
	`36`	`+}`

Comments

(0)