字符串匹配问题：KMP算法

传统字符串匹配和KMP算法

转载时请注明来源：http://blog.csdn.net/ccfeng2008

JAVA源码如下：

/* * @class StringMatching.java * @author ccfeng * @date 2013-10-5 *  * */package kmp;import static java.lang.System.out;import java.util.ArrayList;import java.util.List;public class StringMatching {public static int traditional(char[] targets, char[] patterns) {if (targets == null || targets.length == 0 || patterns == null|| patterns.length == 0)return -1;int index = -1;for (int tIndex = 0, tLen = targets.length, pLen = patterns.length; tIndex < tLen; tIndex++) {int tmp = tIndex;for (int pIndex = 0; pIndex < pLen && tmp < tLen&& targets[tmp++] == patterns[pIndex]; pIndex++) {if (pIndex == pLen - 1)index = tIndex;}if (index != -1)break;}return index;}public static Integer[] traditionals(char[] targets, char[] patterns) {if (targets == null || targets.length == 0 || patterns == null|| patterns.length == 0)return new Integer[0];List<Integer> indexList = new ArrayList<Integer>();for (int tIndex = 0, tLen = targets.length, pLen = patterns.length; tIndex < tLen; tIndex++) {int tmp = tIndex;for (int pIndex = 0; pIndex < pLen && tmp < tLen&& targets[tmp++] == patterns[pIndex]; pIndex++) {if (pIndex == pLen - 1)indexList.add(tIndex);}}return indexList.toArray(new Integer[indexList.size()]);}public static Integer[] kmps(char[] targets, char[] patterns) {if (targets == null || targets.length == 0 || patterns == null|| patterns.length == 0)return new Integer[0];List<Integer> indexList = new ArrayList<Integer>();int[] cPFs = cptPfFunc(patterns);int pIndex = 0;for (int tIndex = 0, tLen = targets.length, pLen = patterns.length; tIndex < tLen; tIndex++) {while (pIndex > 0 && patterns[pIndex] != targets[tIndex])pIndex = cPFs[pIndex - 1];if (patterns[pIndex] == targets[tIndex])pIndex++;if (pIndex == pLen) {indexList.add(tIndex - pLen + 1);pIndex = cPFs[pIndex - 1];}}return indexList.toArray(new Integer[indexList.size()]);}public static int kmp(char[] targets, char[] patterns) {if (targets == null || targets.length == 0 || patterns == null|| patterns.length == 0)return -1;int index = -1;int[] cPFs = cptPfFunc(patterns);int pIndex = 0;for (int tIndex = 0, tLen = targets.length, pLen = patterns.length; tIndex < tLen; tIndex++) {while (pIndex > 0 && patterns[pIndex] != targets[tIndex])pIndex = cPFs[pIndex - 1];if (patterns[pIndex] == targets[tIndex])pIndex++;if (pIndex == pLen)index = tIndex - pLen + 1;if (index != -1)break;}return index;}public static int[] cptPfFunc(char[] patterns) {int size = patterns.length;int[] cPFs = new int[size];cPFs[0] = 0;int cIndex = 0;for (int pIndex = 1; pIndex < size; pIndex++) {while (cIndex > 0 && patterns[cIndex] != patterns[pIndex])cIndex = cPFs[cIndex];if (patterns[cIndex] == patterns[pIndex])cIndex++;cPFs[pIndex] = cIndex;}return cPFs;}public static void main(String[] args) {char[] targets = "kkabcdefijklmnabcdefijkabcdlmn".toCharArray();char[] patterns = "abcd".toCharArray();out.println("-------------First Matching Index-----------------");out.println("traditional first match: "+ traditional(targets, patterns));out.println("kmp first match: " + kmp(targets, patterns));out.println("-------------Traditional Matching Array-----------------");Integer[] tIndexs = traditionals(targets, patterns);for (int i = 0, tLen = tIndexs.length; i < tLen; i++) {out.print(tIndexs[i] + " ");}out.println("\n-------------KMP Matching Array-----------------");Integer[] kmpIndexs = kmps(targets, patterns);for (int i = 0, kmpLen = kmpIndexs.length; i < kmpLen; i++) {out.print(kmpIndexs[i] + " ");}}}

测试结果：

-------------First Matching Index-----------------
traditional first match: 2
kmp first match: 2
-------------Traditional Matching Array-----------------
2 14 23
-------------KMP Matching Array-----------------
2 14 23