70 lines
1.6 KiB
Java
70 lines
1.6 KiB
Java
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import java.util.Arrays;
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public class StringDistances {
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// https://en.wikipedia.org/wiki/Longest_common_subsequence_problem
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public static int[] getLCS(int[] x, int[] y) {
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int m = x.length;
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int n = y.length;
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int[][] lcs = new int[m + 1][n + 1];
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for (int i = 0; i < m; i++) {
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for (int j = 0; j < n; j++) {
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if (x[i] == y[j]) {
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lcs[i + 1][j + 1] = lcs[i][j] + 1;
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} else {
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lcs[i + 1][j + 1] = Math.max(lcs[i + 1][j], lcs[i][j + 1]);
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}
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}
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}
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int cnt = lcs[m][n];
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int[] res = new int[cnt];
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for (int i = m - 1, j = n - 1; i >= 0 && j >= 0; ) {
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if (x[i] == y[j]) {
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res[--cnt] = x[i];
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--i;
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--j;
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} else if (lcs[i + 1][j] > lcs[i][j + 1]) {
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--j;
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} else {
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--i;
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}
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}
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return res;
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}
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// https://en.wikipedia.org/wiki/Levenshtein_distance
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public static int getLevensteinDistance(String a, String b) {
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int m = a.length();
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int n = b.length();
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int[][] len = new int[m + 1][n + 1];
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for (int i = 0; i <= m; i++) {
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len[i][0] = i;
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}
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for (int j = 0; j <= n; j++) {
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len[0][j] = j;
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}
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for (int i = 0; i < m; i++) {
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for (int j = 0; j < n; j++) {
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if (a.charAt(i) == b.charAt(j)) {
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len[i + 1][j + 1] = len[i][j];
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} else {
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len[i + 1][j + 1] = 1 + Math.min(len[i][j], Math.min(len[i + 1][j], len[i][j + 1]));
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}
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}
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}
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return len[m][n];
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}
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// Usage example
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public static void main(String[] args) {
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int[] x = {1, 5, 4, 2, 3, 7, 6};
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int[] y = {2, 7, 1, 3, 5, 4, 6};
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int[] lcs = getLCS(x, y);
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System.out.println(Arrays.toString(lcs));
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String a = "abc";
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String b = "ac";
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System.out.println(getLevensteinDistance(a, b));
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}
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}
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