ACM-ICPC-OJ训练营

问题 2459 --Skiing

2459: Skiing

时间限制: 1 Sec 内存限制: 128 MB
提交: 0 解决: 0
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题目描述

Bessie and the rest of Farmer John's cows are taking a trip this winter to go skiing. One day Bessie finds herself at the top left corner of an R (1 <= R <= 100) by C (1 <= C <= 100) grid of elevations E (-25 <= E <= 25). In order to join FJ and the other cows at a discow party, she must get down to the bottom right corner as quickly as she can by travelling only north, south, east, and west.

Bessie starts out travelling at a initial speed V (1 <= V <= 1,000,000). She has discovered a remarkable relationship between her speed and her elevation change. When Bessie moves from a location of height A to an adjacent location of eight B, her speed is multiplied by the number 2^(A-B). The time it takes Bessie to travel from a location to an adjacent location is the reciprocal of her speed when she is at the first location.

Find the both smallest amount of time it will take Bessie to join her cow friends.

输入描述

* Line 1: Three space-separated integers: V, R, and C, which respectively represent Bessie's initial velocity and the number of rows and columns in the grid.

* Lines 2..R+1: C integers representing the elevation E of the corresponding location on the grid.

输出描述

A single number value, printed to two exactly decimal places: the minimum amount of time that Bessie can take to reach the bottom right corner of the grid.

样例输入

样例输出

29.00

提示

Bessie's best route is:

Start at 1,1 time 0 speed 1

East to 1,2 time 1 speed 1/16

South to 2,2 time 17 speed 1/4

South to 3,2 time 21 speed 1/8

East to 3,3 time 29 speed 1/4

来源

19刘力宾

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