P1163 银行贷款

假设 n为贷款的原值，m为每月支付的分期付款金额，k为分期付款还清贷款所需的总月数，且利率按月累计。
利率为p,则

就好比如，你第一个月的利率为（1+p）,第二个月的利率就为（1+p）^2,依次类推。
（银行利率不太懂，简单记录一下）

    import java.io.BufferedReader;
    import java.io.InputStreamReader;
    import java.io.StreamTokenizer;
    import java.util.Arrays;
    import java.util.Comparator;
    import java.util.Scanner;

    public class Main {
    
        public static void main(String[] args) throws Exception{
    
            Scanner sc = new Scanner(System.in);
            int n = sc.nextInt();
            int m = sc.nextInt();
            int k = sc.nextInt();
            double l=0;
            double r=10;
            double mid=0;
            while(r-l>=0.0001){
    
                mid = (l+r)/2;
                if(judge(mid,k,n,m)){
    
                    l = mid;
                }
                else
                    r=mid;
            }
            System.out.println(String.format("%.1f",mid*100));
        }
    
        public static boolean judge(double mid,int k,int n,int m){
    
            double sum=0;
            for(int i=1;i<=k;i++){
    
                sum+=(double)1/Math.pow(1+mid,i);
            }
            return sum>=(double)n/m;
        }
    }

    class Node{
    
        int x,y;
    }

    class cmp implements Comparator<Node> {
    

        @Override
        public int compare(Node o1, Node o2) {
    

            return o1.y - o2.y;
        }

    }
    //快读
    class Read{
    
        StreamTokenizer st=new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
        public int nextInt() throws Exception{
    
            st.nextToken();
            return (int)st.nval;
        }
    }