分贝壳

使用二分查找下界的思想。

将mid作为妞妞一次拿多少的值

如果当前的mid满足“妞妞想要得到不少于一半的贝壳”，

则记录下当前mid的值，并继续向左查找。

否则就是mid值太小，向右查找
public class 分贝壳 {

public static void main(String[] args) {

Scanner input = new Scanner(System.in);
long n = input.nextLong();
long start = 1;
long end = n;
long temp = 0;
while (start < end) {
    long mid = start+(end-start)/2;
    if (minNum(mid,n)) {
        temp = mid;
        end = mid;
    }else {
        start = mid+1;
    }
}
System.out.println(temp);
}
private static boolean minNum(long m,long n) {        //m为妞妞一次拿多少，n为贝克总数 long num1 = 0;            //妞妞拿的贝壳数
long temp = n;            //剩下的贝壳总数
long mid = 0;
while (temp>=0) {
    if (temp < m) {
        num1 += temp;
        break;
    }
    num1 += m;
    temp -= m;
    temp -= temp/10;
}
if (n%2 == 0)
     mid = n/2;
else
    mid = (n+1)/2;

return num1>=mid?true:false;
}
}