Arranging coins.

Author: recherst

Easy/441.Arranging Coins.playground/Contents.swift

@@ -0,0 +1,32 @@
+/**
+ You have n coins and you want to build a staircase with these coins. The staircase consists of k rows where the ith row has exactly i coins. The last row of the staircase may be incomplete.
+
+ Given the integer n, return the number of complete rows of the staircase you will build.
+
+  
+
+ Example 1:
+ Input: n = 5
+ Output: 2
+ Explanation: Because the 3rd row is incomplete, we return 2.
+ 
+ Example 2:
+ Input: n = 8
+ Output: 3
+ Explanation: Because the 4th row is incomplete, we return 3.
+ */
+class Solution {
+    func arrangeCoins(_ n: Int) -> Int {
+        if n == 1 || n == 2 { return 1 }
+        if n == 3 { return 2 }
+        var k = 3
+        while (n - k * (k - 1) / 2 > 0) && (n - k * (k - 1) / 2 > k) {
+            k += 1
+        }
+        return n - k * (k - 1) / 2 == k ? k : k - 1
+    }
+}
+
+let s = Solution()
+let r = s.arrangeCoins(3)
+print(r)

Easy/441.Arranging Coins.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

Easy/441.Arranging Coins.playground/playground.xcworkspace/contents.xcworkspacedata

@@ -88,6 +88,7 @@
 84. [Third Maximum Number](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/414.Third%20Maximum%20Number.playground/Contents.swift)
 85. [Add Strings](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/415.Add%20Strings.playground/Contents.swift)
 86. [Number of Segments in a String](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/434.Number%20of%20Segments%20in%20a%20String.playground/Contents.swift)
+87. [Arranging Coins](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/441.Arranging%20Coins.playground/Contents.swift)
 
 #### Medium