刷题

2、findFirstOneTimeChar

算法
阅读次数: 0
本文字数: 153 阅读时长: 1 分钟

题目

请实现一个函数，输入一个字符串，找出第一个只出现一次的字符。

输入

“asdfasdfo”

输出

‘o’

实现

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
public static char findFirstOneTimeChar(String input) {
    if (input == null || input.length() <= 0) {
        return 0;
    }
    char[] chars = input.toCharArray();
    final int[] numArray = new int[256];
    for (char curChar : chars) {
        numArray[curChar]++;
    }
    for (char curChar : chars) {
        if (numArray[curChar] == 1) {
            return curChar;
        }
    }
    return 0;
}

单元测试

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
public class FindFirstOneTimeCharTest {

    @Test
    public void testNulInput() {
        Assert.assertEquals(FindFirstOneTimeChar.findFirstOneTimeChar(null), 0);
    }

    @Test
    public void testEmptyInput() {
        Assert.assertEquals(FindFirstOneTimeChar.findFirstOneTimeChar(""), 0);
    }

    @Test
    public void testSpaceInput() {
        Assert.assertEquals(FindFirstOneTimeChar.findFirstOneTimeChar(" "), ' ');
    }

    @Test
    public void testNormalInput() {
        String input = "asdfasdfo";
        char expect = 'o';
        char result = FindFirstOneTimeChar.findFirstOneTimeChar(input);
        Assert.assertEquals(expect, result);
    }
}