3209045_ac_16ms_324k.cc

北大大牛代码 1240道题的原代码 超级权威

#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <math.h>
using namespace std;

const int N = 1000;
const double EPS = 1e-7;

struct E { double a, b; } e[N];
int n, d;
bool ava[N];
double p[N];

inline int dblcmp(double a, double b) {
 if( fabs(a-b) < EPS ) return 0;
 if( a-b > 0 ) return 1;
 return -1;
}

bool operator<(const E& a, const E& b) {
 if(dblcmp(a.a, b.a) == 0) 
  return dblcmp(a.b, b.b) == 1;
 return dblcmp(a.a, b.a) == -1;
}


int main() {
 int i, j, x, y;
 int tc = 0;
 while(scanf("%d %d", &n, &d), n + d) {
  tc++;
  int ok = 1;
  for(i = 0; i < n; ++i) {
   scanf("%d %d", &x, &y);
   if(y > d) ok = 0;
   double offset = sqrt ( d * d - y * y );
   e[i].a = x - offset, e[i].b = x + offset;
   ava[i] = 1;
  }
  if(!ok) { printf("Case %d: -1\n", tc); continue; }
  sort(e, e + n);
  int stack[N], top = 0;
  stack[top++] = 0;
  for(i = 1; i < n; ++i) {
   while(top > 0 && dblcmp(e[stack[top-1]].b, e[i].b) != -1)  {
    ava[stack[--top]] = 0;
   }
   stack[top++] = i;
  }
  
  for(i = 0; !ava[i]; ++i);
  p[i] = e[i].b;
  int cnt = 1;
  for(i = i+1; i < n; ++i) if(ava[i]) {
   for(j = i-1; !ava[j]; j--);
   if(p[j] >= e[i].a)  p[i] = p[j]; 
   else { p[i] = e[i].b; cnt++; }
  }
  printf("Case %d: %d\n", tc, cnt);
 }
 return 0;
}