力扣AC：旋转字符串 - 思想

题目链接

旋转字符串

题目描述

实现代码

个人思路实现代码：

class Solution {
    public boolean rotateString(String s, String goal) {
        int m = s.length();
        int n = goal.length();
        if(m != n) {
            return false;
        }
        char firstG = goal.charAt(0);
        for(int i=0; i<m; i++) {
            char curS = s.charAt(i);
            if(curS == firstG) {
                int j = i+1;
                int k = 1;
                boolean access = true;
                for(; j<m & k<n; j++, k++) {
                    if(s.charAt(j) != goal.charAt(k)) {
                        access = false;
                        break;
                    }
                }
                if(access) {
                    for (j = 0; j < i; j++) {
                        if (s.charAt(j) != goal.charAt(k + j)) {
                            access = false;
                            break;
                        }
                    }
                }
                if(access) {
                    return true;
                }
            }
        }
        return false;
    }
}

参考思路一：源字符串拼接寻找子串思想：

class Solution {
    public boolean rotateString(String s, String goal) {
        return s.length() == goal.length() && (s + s).contains(goal);
    }
}

参考思路二：数学思想：

class Solution {
    public boolean rotateString(String s, String goal) {
        int m = s.length(), n = goal.length();
        if (m != n) {
            return false;
        }
        for (int i = 0; i < n; i++) {
            boolean flag = true;
            for (int j = 0; j < n; j++) {
                if (s.charAt((i + j) % n) != goal.charAt(j)) {
                    flag = false;
                    break;
                }
            }
            if (flag) {
                return true;
            }
        }
        return false;
    }
}