Recently Petya has discovered new game with points. Rules of the game are quite simple. First, there is only one point A0 with coordinates (0, 0). Then Petya have to draw N another points. Points must be drawn consequently and each new point must be connected with exactly one of the previous points by a segment. Let's decribe the game process more formally. At the i-th step Petya chooses the position of the point Ai (not necessarily with integer coordinates). Than he chooses one of the previously drawn points in order to connect it with the point Ai. Lets call this point B. The following conditions must be held:
sample input |
sample output |
2 |
5.000 |
sample input |
sample output |
4 |
20.000 1 #include<iostream> 2 #include<string.h> 3 #include<stdio.h> 4 #include<ctype.h> 5 #include<algorithm> 6 #include<stack> 7 #include<queue> 8 #include<set> 9 #include<math.h> 10 #include<vector> 11 #include<map> 12 #include<deque> 13 #include<list> 14 using namespace std; 15 int a[1111]; 16 int b[1111]; 17 18 int main() 19 { 20 //freopen("in.txt", "r", stdin); 21 int n; 22 scanf("%d", &n); 23 a[1] = 1; 24 b[1] = 1; 25 26 if (n == 0) printf("0.000\n"); 27 else if (n == 1)printf("1.000\n"); 28 else if (n == 2)printf("5.000\n"); 29 else 30 { 31 double ans = 5; 32 int m = 2, d = 2; 33 for (int i = 2; i <n; i++) 34 { 35 if ((m + 1)*d >= m*(d + 1)) 36 m++; 37 else 38 d++; 39 ans += m*d; 40 } 41 printf("%.3lf\n", ans); 42 } 43 44 return 0; 45 }
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