标签：max const ack bridge rip file bsp queue for
题目链接：https://cn.vjudge.net/problem/142542/origin
You need to design road from (0, 0) to (x, y) in plane with the lowest cost. Unfortunately, there are N Rivers between (0, 0) and (x, y).It costs c1 Yuan RMB per meter to build road, and it costs c2 Yuan RMB per meter to build a bridge. All rivers are parallel to the Y axis with infinite length.
There are several test cases.
Each test case contains 5 positive integers N,x,y,c1,c2 in the first line.(N ≤ 1000,1 ≤ x,y≤ 100,000,1 ≤ c1,c2 ≤ 1000).
The following N lines, each line contains 2 positive integer xi, wi ( 1 ≤ i ≤ N ,1 ≤ xi ≤x, xi-1+wi-1 < xi , xN+wN ≤ x),indicate the i-th river(left bank) locate xi with wi width.
The input will finish with the end of file.
For each the case, your program will output the least cost P on separate line, the P will be to two decimal places .
1 300 400 100 100 100 50 1 150 90 250 520 30 120
50000.00 80100.00
给你一个二维的坐标系，你要从[0,0]走到[x,y]。但是其间会有一些平行于y轴的河，你需要架桥。给你每米的修路费，和每米的修桥费，问最少的费用是多少？
1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #include <cstdlib> 5 #include <string> 6 #include <vector> 7 #include <map> 8 #include <set> 9 #include <queue> 10 #include <sstream> 11 #include <cmath> 12 #include <algorithm> 13 using namespace std; 14 #define pb push_back 15 #define mp make_pair 16 #define exp 1e-7 17 #define ms(a, b) memset((a), (b), sizeof(a)) 18 //#define LOCAL 19 typedef long long LL; 20 const int inf = 0x3f3f3f3f; 21 const int maxn = 200000+10; 22 const int mod = 1000000007; 23 double n, x, y, c1, c2, riverlen, landlen; 24 double cut(double hh) 25 { 26 return c2*hypot(riverlen, hh) + c1*hypot(landlen, y-hh); 27 } 28 int main() { 29 #ifdef LOCAL 30 freopen("input.txt" , "r", stdin); 31 #endif // LOCAL 32 while(~scanf("%lf%lf%lf%lf%lf", &n, &x, &y, &c1, &c2)){ 33 riverlen = 0.0; 34 for(int i=0;i<n;i++){ 35 double xi, wi; 36 scanf("%lf%lf", &xi, &wi); 37 riverlen += wi; 38 } 39 landlen = x - riverlen; 40 double l , r, mid, mmid; 41 l = 0; 42 r = y; 43 while( l + exp < r){ 44 mid = ( l + r ) / 2; 45 mmid = (mid + r) / 2; 46 if( cut(mid) <= cut(mmid) ) 47 r = mmid; 48 else 49 l = mid; 50 } 51 printf("%.2f\n", cut(l)); 52 } 53 return 0; 54 }
标签：max const ack bridge rip file bsp queue for
原文地址：http://www.cnblogs.com/denghaiquan/p/6741544.html
