LeetCode面试题 01.09 字符串轮转

题目

解答

package leetcode.editor.cn;

//leetcode submit region begin(Prohibit modification and deletion)
class Solution {
    public boolean isFlipedString(String s1, String s2) {
        if (s1 == null && s2 == null) {
            return true;
        }

        if (s1 == null || s2 == null) {
            return false;
        }

        if (s1.isEmpty() && s2.isEmpty()) {
            return true;
        }

        if (s1.length() != s2.length()) {
            return false;
        }

        for (int i = 0, length = s1.length(); i < length; ++i) {
            String ss1 = s1.substring(i);
            if (s2.startsWith(ss1)) {
                if (s2.equals(s1.substring(i, s1.length()) + s1.substring(0, i))) {
                    return true;
                }
            }
        }

        return false;
    }
}
//leetcode submit region end(Prohibit modification and deletion)

测试用例

package leetcode.editor.cn;

import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;

public class SolutionTest {
    private Solution s = null;

    @Before
    public void setUp() throws Exception {
        s = new Solution();
    }

    @Test
    public void test1() {
        Assert.assertTrue(s.isFlipedString("waterbottle", "erbottlewat"));
        Assert.assertTrue(s.isFlipedString("erbottlewat", "waterbottle"));
    }

    @Test
    public void test2() {
        Assert.assertFalse(s.isFlipedString("aa", "aba"));
        Assert.assertFalse(s.isFlipedString("aba", "aa"));
    }

    @Test
    public void test3() {
        Assert.assertTrue(s.isFlipedString("waterbottle", "waterbottle"));
    }

    @Test
    public void test4() {
        Assert.assertFalse(s.isFlipedString("abcd", "acdb"));
    }
}

理解并掌握String的startsWith和substring的使用方法。