106 miles to Chicago(一)

Time Limit:5000MS Memory Limit:32768KB 64bit IO Format:%lld & %lld

Description

In the movie "Blues Brothers", the orphanage where Elwood and Jack were raised may be sold to the Board of Education if they do not pay 5000 dollars in taxes at the Cook Country Assessor's Office in Chicago. After playing a gig in the Palace Hotel ballroom to earn these 5000 dollars, they have to find a way to Chicago. However, this is not so easy as it sounds, since they are chased by the Police, a country band and a group of Nazis. Moreover, it is 106 miles to Chicago, it is dark and they are wearing sunglasses.
As they are on a mission from God, you should help them find the safest way to Chicago. In this problem, the safest way is considered to be the route which maximises the probability that they are not caught.

Input Specification

The input file contains several test cases.
Each test case starts with two integers n and m (2 ≤ n ≤ 100 ,1 ≤ m ≤ n*(n-1)/2). n is the number of intersections, m is the number of streets to be considered.
The next m lines contain the description of the streets. Each street is described by a line containing 3 integersa, b and p (1 ≤ a, b ≤ n , a ≠ b, 1 ≤ p ≤ 100): a and b are the two end points of the street andp is the probability in percent that the Blues Brothers will manage to use this street without being caught. Each street can be used in both directions. You may assume that there is at most one street between two end points.
The last test case is followed by a zero.

Output Specification

For each test case, calculate the probability of the safest path from intersection1 (the Palace Hotel) to intersection n (the Honorable Richard J. Daley Plaza in Chicago). You can assume that there is at least one path between intersection1 and n.
Print the probability as a percentage with exactly 6 digits after the decimal point. The percentage value is considered correct if it differs by at most 10^-6 from the judge output. Adhere to the format shown below and print one line for each test case.

Sample Input

5 7
5 2 100
3 5 80
2 3 70
2 1 50
3 4 90
4 1 85
3 1 70
0

Sample Output

61.200000 percent

Input

The input file contains several test cases.
Each test case starts with two integers n and m (2 ≤ n ≤ 100 ,1 ≤ m ≤ n*(n-1)/2). n is the number of intersections, m is the number of streets to be considered.
The next m lines contain the description of the streets. Each street is described by a line containing 3 integersa, b and p (1 ≤ a, b ≤ n , a ≠ b, 1 ≤ p ≤ 100): a and b are the two end points of the street andp is the probability in percent that the Blues Brothers will manage to use this street without being caught. Each street can be used in both directions. You may assume that there is at most one street between two end points.
The last test case is followed by a zero.

Output

For each test case, calculate the probability of the safest path from intersection1 (the Palace Hotel) to intersection n (the Honorable Richard J. Daley Plaza in Chicago). You can assume that there is at least one path between intersection1 and n.
Print the probability as a percentage with exactly 6 digits after the decimal point. The percentage value is considered correct if it differs by at most 10^-6 from the judge output. Adhere to the format shown below and print one line for each test case.

Sample Input

5 7
5 2 100
3 5 80
2 3 70
2 1 50
3 4 90
4 1 85
3 1 70
0

Sample Output

61.200000 percent

题目解析：

题目说给出m条边，n个点。叫你求出其中可以组成的最长路。一道图论的水题。居然比赛时候没看该题没做出来！！！真想说what fack are you doing!!!!说自己搞图论的，到现在为止现场比赛中没做出过一道图论题。cao!!!

思路解析：

我们可以