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KSimilarStrings.java
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KSimilarStrings.java
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package com.algorithm.playground.leetcode.problems.lc800.lc850.lc854;
import java.util.ArrayDeque;
import java.util.HashSet;
import java.util.Queue;
import java.util.Set;
/**
* https://leetcode.com/problems/k-similar-strings/description/
*/
public class KSimilarStrings {
class Solution {
public int kSimilarity(String A, String B) {
Queue<String> queue = new ArrayDeque<>();
Set<String> seen = new HashSet<>();
queue.add(A);
seen.add(A);
int steps = -1;
while (!queue.isEmpty()) {
int size = queue.size();
steps++;
while (size > 0) {
String curr = queue.poll();
size--;
//noinspection ConstantConditions
if (curr.equals(B)) {
return steps;
}
StringBuilder builder = new StringBuilder(curr);
for (int i = 0; i < B.length(); i++) {
char ch = B.charAt(i);
if (builder.charAt(i) == ch) {
continue;
}
for (int j = i + 1; j < builder.length(); j++) {
if (builder.charAt(j) != B.charAt(j) && builder.charAt(j) == ch) {
swap(builder, i, j);
String s = builder.toString();
if (seen.add(s)) {
queue.add(s);
}
swap(builder, j, i);
}
}
break;
}
}
}
return 0;
}
private void swap(StringBuilder builder, int i1, int i2) {
char ch = builder.charAt(i1);
builder.setCharAt(i1, builder.charAt(i2));
builder.setCharAt(i2, ch);
}
}
}