[leetcode 87 擾亂字串] [剪枝搜尋]

import java.util.HashMap;
import java.util.Map;

class Solution {
    public static void main(String[] args) {
        Solution solution = new Solution();
        boolean res = solution.isScramble("eebaacbcbcadaaedceaaacadccd", "eadcaacabaddaceacbceaabeccd");
        System.out.println(res);
    }
    public boolean isScramble(String s1, String s2) {
        return isRaoluanStr(s1, s2);
    }

    public boolean isSame(String s1, int from1, String s2, int from2, int len) {
        int[] arr = new int[26];
        for (int i = 0; i < len; i++) {
            arr[s1.charAt(from1 + i) - 'a']++;
            arr[s2.charAt(from2 + i) - 'a']--;
        }
        for (int i = 0; i < len; i++) {
            if (arr[s1.charAt(from1 + i) - 'a'] != 0) {
                return false;
            }
            if (arr[s2.charAt(from2 + i) - 'a'] != 0) {
                return false;
            }
        }
        return true;
    }

    public boolean isEqual(String s1, String s2, int splitIndex) {
        return isSame(s1, 0, s2, 0, splitIndex + 1)
                && isSame(s1, splitIndex + 1, s2, splitIndex + 1, s1.length() - splitIndex - 1);
    }

    public boolean isYxSame(String s1, String s2, int splitIndex) {
        // s1 y,x
        int n = s1.length();
        int xlen = splitIndex + 1;
        int ylen = n - xlen;
        String y = s1.substring(n - ylen);
        String x = s1.substring(0, xlen);
        // s2 x,y
        String x1 = s2.substring(0, ylen);
        String y1 = s2.substring(ylen);

        return isSame(y, 0, x1, 0, ylen) && isSame(x, 0, y1, 0, xlen);
    }

    Map<String,Map<String,Boolean>> map = new HashMap<>();
    public boolean isRaoluanStr(String s1, String s2) {
        if (s1.length() != s2.length()) {
            return false;
        }
        if (s1.length() == 1) {
            if (s1.charAt(0) == s2.charAt(0)) {
                return true;
            }
            return false;
        }
        if (map.get(s1) != null && map.get(s1).get(s2) != null) {
            return map.get(s1).get(s2);
        }
        // 分割
        boolean ans = false;
        int n = s1.length();
        for (int split = 0; split < n - 1; split++) {
            if (isEqual(s1, s2, split)) {
                // 可以切割s1, s2;
                ans |= isRaoluanStr(s1.substring(0, split + 1), s2.substring(0, split + 1))
                        && isRaoluanStr(s1.substring(split + 1), s2.substring(split + 1));
                if (ans) {
                   break;
                }
            }
            if (isYxSame(s1, s2, split)) {
                ans |= isRaoluanStr(s1.substring(split + 1), s2.substring(0, s1.length() - split - 1))
                        && isRaoluanStr(s1.substring(0, split + 1), s2.substring(s1.length() - split - 1));
                if (ans) {
                  break;
                }
            }
        }
        map.put(s1, map.getOrDefault(s1,new HashMap<>()));
        map.get(s1).put(s2, ans);
        map.put(s2, map.getOrDefault(s2, new HashMap<>()));
        map.get(s2).put(s1, ans);
        return ans;
    }
}