poj2354Titanic(两点的球面距离)
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。
1 #include <iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include<algorithm> 5 #include<stdlib.h> 6 #include<vector> 7 #include<cmath> 8 #include<queue> 9 #include<set> 10 using namespace std; 11 #define N 100000 12 #define LL long long 13 #define INF 0xfffffff 14 const double eps = 1e-8; 15 const double pi = acos(-1.0); 16 const double inf = ~0u>>2; 17 const double r = 6875/2.0; 18 char s[110]; 19 int dcmp(double x) 20 { 21 if(fabs(x)<eps) return 0; 22 return x<0?-1:1; 23 } 24 void solve(double x1,double y1,double x2,double y2) 25 { 26 double ans = r*acos(sin(x1)*sin(x2)+ 27 cos(x1)*cos(x2)*cos(y1-y2)); 28 29 printf("The distance to the iceberg: %.2lf miles.\n",ans); 30 if(dcmp(ans-100+0.005)<0) 31 puts("DANGER!"); 32 } 33 int main() 34 { 35 double d1,d2,d3,d4; 36 int a,b,c,i; 37 char dir[10]; 38 for(i = 0; i < 9 ; i++) 39 scanf("%s",s); 40 scanf("%s",s); 41 sscanf(s,"%d^%d'%d''",&a,&b,&c); 42 //printf("%d %d %d\n",a,b,c); 43 d1 = a+b/60.0+c/3600.0; 44 scanf("%s",dir); 45 if(dir[0]=='S') 46 d1=-d1; 47 scanf("%s",s); 48 49 scanf("%s",s); 50 sscanf(s,"%d^%d'%d''",&a,&b,&c); 51 //printf("%d %d %d\n",a,b,c); 52 d2 = a+b/60.0+c/3600.0; 53 scanf("%s",dir); 54 if(dir[0]=='W') 55 d2=-d2; 56 57 for(i =0 ; i < 5 ; i++) scanf("%s",s); 58 scanf("%s",s); 59 sscanf(s,"%d^%d'%d''",&a,&b,&c); 60 //printf("%d %d %d\n",a,b,c); 61 d3 = a+b/60.0+c/3600.0; 62 scanf("%s",dir); 63 if(dir[0]=='S') 64 d3=-d3; 65 66 scanf("%s",s); 67 68 scanf("%s",s); 69 sscanf(s,"%d^%d'%d''",&a,&b,&c); 70 //printf("%d %d %d\n",a,b,c); 71 d4 = a+b/60.0+c/3600.0; 72 scanf("%s",dir); 73 if(dir[0]=='W') 74 d4=-d4; 75 scanf("%s",s); 76 77 solve(d1*pi/180,d2*pi/180,d3*pi/180,d4*pi/180); 78 return 0; 79 }
