标签:oop pue logs bottom int world and task ignore
InputThe first line contains two integers R and C (2 <= R, C <= 1000).
The following R lines, each contains C*3 real numbers, at 2 decimal places. Every three numbers make a group. The first, second and third number of the cth group of line r represent the probability of transportation to grid (r, c), grid (r, c+1), grid (r+1, c) of the portal in grid (r, c) respectively. Two groups of numbers are separated by 4 spaces.
It is ensured that the sum of three numbers in each group is 1, and the second numbers of the rightmost groups are 0 (as there are no grids on the right of them) while the third numbers of the downmost groups are 0 (as there are no grids below them).
You may ignore the last three numbers of the input data. They are printed just for looking neat.
The answer is ensured no greater than 1000000.
Terminal at EOF
OutputA real number at 3 decimal places (round to), representing the expect magic power Homura need to escape from the LOOPS.
2 2
0.00 0.50 0.50 0.50 0.00 0.50
0.50 0.50 0.00 1.00 0.00 0.00
6.000
题意: R 行 C 列的迷宫,起点 (1,1) ,终点(R,C) ,然后给出每个格子的留在原地的概率,向右的概率,向下的概率,走一步 2 的魔法,问能逃出去的耗费的魔法期望
题解:一般做法,dp [i][j] 代表从(i,j)逃出去的魔法消耗期望,值得注意的是如果这点停在原地概率为 1 的话,这点的 dp[][]值应该为 0 ,因为不能进去,进去就是死,要求的是能逃得出的魔法消耗期望
1 #include <iostream> 2 #include <stdio.h> 3 #include <string.h> 4 #include <math.h> 5 using namespace std; 6 #define MAXN 1005 7 const double eps = 1e-8; 8 9 struct Pro 10 { 11 double s; 12 double r; 13 double d; 14 }p[MAXN][MAXN]; 15 16 int n,m; 17 double dp[MAXN][MAXN]; 18 19 int main() 20 { 21 while (scanf("%d%d",&n,&m)!=EOF) 22 { 23 for (int i=1;i<=n;i++) 24 for (int j=1;j<=m;j++) 25 scanf("%lf%lf%lf",&p[i][j].s,&p[i][j].r,&p[i][j].d); 26 memset(dp,0,sizeof(dp)); 27 for (int i=n;i>=1;i--) 28 for (int j=m;j>=1;j--) 29 { 30 if (i==n&&m==j) continue; 31 if (1-p[i][j].s<eps) continue; //如果在这点必死,则dp值继续保持 0 代表不能来 32 dp[i][j]=(p[i][j].r*dp[i][j+1] 33 +p[i][j].d*dp[i+1][j] 34 +2)/(1-p[i][j].s); 35 } 36 printf("%.3lf\n",dp[1][1]); 37 } 38 return 0; 39 }
标签:oop pue logs bottom int world and task ignore
原文地址:http://www.cnblogs.com/haoabcd2010/p/6701063.html