poj2354Titanic(两点的球面距离)

链接

球面距离计算公式：d(x1,y1,x2,y2)=r*arccos(sin(x1)*sin(x2)+cos(x1)*cos(x2)*cos(y1-y2))

x1,y1是纬度\经度的弧度单位，r为地球半径

把有用的信息从恶心的字符串中提取出来，然后套公式，再处理下恶心的精度，得出的距离需要四舍五入。

 #include <iostream>
 #include<cstdio>
 #include<cstring>
 #include<algorithm>
 #include<stdlib.h>
 #include<vector>
 #include<cmath>
 #include<queue>
 #include<set>
 using namespace std;
 #define N 100000
 #define LL long long
 #define INF 0xfffffff
 const double eps = 1e-;
 const double pi = acos(-1.0);
 const double inf = ~0u>>;
 const double r = /2.0;
 char s[];
 int dcmp(double x)
 {
     if(fabs(x)<eps) return ;
     return x<?-:;
 }
 void solve(double x1,double y1,double x2,double y2)
 {
     double ans =  r*acos(sin(x1)*sin(x2)+
                    cos(x1)*cos(x2)*cos(y1-y2));

     printf("The distance to the iceberg: %.2lf miles.\n",ans);
     if(dcmp(ans-+0.005)<)
     puts("DANGER!");
 }
 int main()
 {
     double d1,d2,d3,d4;
     int a,b,c,i;
     char dir[];
     for(i = ; i <  ; i++)
     scanf("%s",s);
     scanf("%s",s);
     sscanf(s,"%d^%d'%d''",&a,&b,&c);
     //printf("%d %d %d\n",a,b,c);
     d1 = a+b/60.0+c/3600.0;
     scanf("%s",dir);
     if(dir[]=='S')
     d1=-d1;
     scanf("%s",s);

     scanf("%s",s);
     sscanf(s,"%d^%d'%d''",&a,&b,&c);
     //printf("%d %d %d\n",a,b,c);
     d2 = a+b/60.0+c/3600.0;
     scanf("%s",dir);
     if(dir[]=='W')
     d2=-d2;

     for(i = ; i <  ; i++) scanf("%s",s);
     scanf("%s",s);
     sscanf(s,"%d^%d'%d''",&a,&b,&c);
     //printf("%d %d %d\n",a,b,c);
     d3 = a+b/60.0+c/3600.0;
     scanf("%s",dir);
     if(dir[]=='S')
     d3=-d3;

     scanf("%s",s);

     scanf("%s",s);
     sscanf(s,"%d^%d'%d''",&a,&b,&c);
     //printf("%d %d %d\n",a,b,c);
     d4 = a+b/60.0+c/3600.0;
     scanf("%s",dir);
     if(dir[]=='W')
     d4=-d4;
     scanf("%s",s);

     solve(d1*pi/,d2*pi/,d3*pi/,d4*pi/);
     return ;
 }