acm解题报告 HDU 2199 Can you solve this equation?

由于方程式单调递增的，所以直接使用二分，找到误差不超过0.00005的解就可以了。

源代码：

#include<stdio.h>
double cal(double a){
 double y = 8 * a*a*a*a + 7 * a*a*a + 2 * a*a + 3 * a + 6;
 return y;
}
double decimal(double a){
 double b=0;
 return b;
}
int main(){
 int t;
 scanf("%d", &t);
 while (t--){
  double y;
  scanf("%lf", &y);
  if (y < 6 || y>807020306)printf("%s\n", "No solution!");
  else {
   double high=100, mid=50, low=0;
   while ((high-low)>=0.000005){
    if (cal(mid) > y){
     high = mid;
     mid = (high + low) / 2;
    }
    else {
     low = mid;
     mid = (high + low) / 2;
    }
   }
   printf("%.4f\n", mid);
  }
 }
 return 0;
}