2017/4/3

XingwenZhang · XingwenZhang · commit 408c77cb135b · 2017-04-03T20:10:55.000-07:00
diff --git a/No441_ArrangingCoins.cpp b/No441_ArrangingCoins.cpp
@@ -0,0 +1,52 @@
+// You have a total of n coins that you want to form in a staircase shape, where every k-th row must have exactly k coins.
+
+// Given n, find the total number of full staircase rows that can be formed.
+
+// n is a non-negative integer and fits within the range of a 32-bit signed integer.
+
+// Example 1:
+
+// n = 5
+
+// The coins can form the following rows:
+// ¤
+// ¤ ¤
+// ¤ ¤
+
+// Because the 3rd row is incomplete, we return 2.
+// Example 2:
+
+// n = 8
+
+// The coins can form the following rows:
+// ¤
+// ¤ ¤
+// ¤ ¤ ¤
+// ¤ ¤
+
+// Because the 4th row is incomplete, we return 3.
+
+
+// class Solution {
+// public:
+// 	// TLE for INT_MAX
+//     int arrangeCoins(int n) {
+//         int count = 0;
+//         int sum = 0;
+//         int i = 1;
+//         while(sum <= n){
+//         	sum += i;
+//         	i++;
+//         	count++;
+//         }
+//         return count-1;
+//     }
+// };
+
+class Solution {
+public:
+	int arrangeCoins(int n) {
+		// 8*n will overflow
+		return int(floor(((sqrt(1 + double(8) * n)) - 1) / 2));
+	}
+};
