[Java] 蓝桥杯PREV-3 历届试题 带分数

问题描述

输入格式

从标准输入读入一个正整数N (N<1000*1000)

输出格式

样例输入1

100

样例输出1

11

样例输入2

105

样例输出2

6

package prev3;
 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
 
public class Main {
 
    public static int cnt = 0, num = 0;
    public static boolean isVisit[] = new boolean[10];
 
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        num = Integer.parseInt(reader.readLine());
        reader.close();
        for (int i = 1; i <= 7; i++) {
            for (int j = 1; j <= 7; j++) {
                if (9 - i - j >= 1) {
                    dfs(0, 0, 0, i, j, 9 -i - j);
                }
            }
        }
        System.out.println(cnt);
    }
 
    public static void dfs(int a, int b, int c, int alen, int blen, int clen) {
        if (alen == 0 && 0 == blen && 0 == clen) {
            if (b % c == 0 && b / c == num - a) {
                cnt++;
            }
            return;
        }
 
        for (int i = 1; i < 10; i++) {
            if (!isVisit[i]) {
                isVisit[i] = true;
                if (0 < alen) {
                    dfs(a * 10 + i, b, c, alen - 1, blen, clen);
                } else if (0 < blen) {
                    dfs(a, b * 10 + i, c, alen, blen - 1, clen);
                } else if (0 < clen) {
                    dfs(a, b, c * 10 + i, alen, blen, clen - 1);
                }
                isVisit[i] = false;
            }
        }
    }
}