HJ5 进制转换

ゝ一世哀愁。 2024-03-27 13:45 35阅读 0赞

> [牛客华为机试题库【题号 HJ开头】（重点看）][HJ]  
> [牛客在线编程算法篇【题号NC开头】][NC]  
> [剑指offer【题号 JZ开头】][offer_ JZ]  
> [力扣][Link 1]

### [1）原题链接][1] ###

### [2）已有题解][2] ###

### 3）代码 ###

package binary;
    
    import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStreamReader;
    import java.util.HashMap;
    import java.util.Map;
    
    import static java.lang.System.in;
    
    public class HexadecimalToDecimal {
        
        private static Map<Character, Integer> map = new HashMap<>() {
        {
        
            put('0', 0);
            put('1', 1);
            put('2', 2);
            put('3', 3);
            put('4', 4);
            put('5', 5);
            put('6', 6);
            put('7', 7);
            put('8', 8);
            put('9', 9);
            put('A', 10);
            put('B', 11);
            put('C', 12);
            put('D', 13);
            put('E', 14);
            put('F', 15);
            put('a', 10);
            put('b', 11);
            put('c', 12);
            put('d', 13);
            put('e', 14);
            put('f', 15);
        }};
    
        public static void main(String[] args) throws IOException {
        
            BufferedReader bf = new BufferedReader(new InputStreamReader(in));
            String hexStr = bf.readLine();
            bf.close();
    
            // 去除前面的额0x
            hexStr = hexStr.substring(2);
            char[] chars = hexStr.toCharArray();
    
    
            // 公式1
            int res = 0;
            for (char aChar : chars) {
        
                res = res * 16 + map.getOrDefault(aChar, 0);
            }
            System.out.println(res);
    
            // 公式2
            int res1 = 0;
            int index = 0;
            for (int i = chars.length - 1; i >= 0; i--) {
        
                Integer orDefault = map.getOrDefault(chars[i], 0);
                res1 += orDefault * Math.pow(16, index++);
            }
            System.out.println(res1);
        }
    }

[HJ]: https://www.nowcoder.com/exam/oj/ta?tpId=37
[NC]: https://www.nowcoder.com/exam/oj
[offer_ JZ]: https://www.nowcoder.com/exam/oj/ta?page=1&tpId=13&type=13
[Link 1]: https://leetcode.cn/problemset/all/
[1]: https://www.nowcoder.com/practice/8f3df50d2b9043208c5eed283d1d4da6?tpId=37&tqId=21228&rp=1&ru=/exam/oj/ta&qru=/exam/oj/ta&sourceUrl=/exam/oj/ta?tpId=37&difficulty=undefined&judgeStatus=undefined&tags=&title=
[2]: https://juejin.cn/post/7101464003129376782