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KMP算法-C++实现

KMP算法的C++实现,Macos下Xcode编译通过

代码如下:

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#include<vector>
#include<iostream>
#include<stdlib.h>

using namespace std;

void cal_next_array(int pattern_length , char * pattern_str , int next[]){
int k = -1;
next[0] = k;
for (int i = 1; i < pattern_length; i ++) {
while ( k > -1 && pattern_str[k+1] != pattern_str[i]) {
k = next[k];
}
if( pattern_str[k+1] == pattern_str[i] ){
k ++;
}
next[i] = k;
}
}

int kmp( char * source , char * pattern , int sourceLength , int patternLength ){
if( patternLength <= 0 || sourceLength <= 0 || sourceLength < patternLength || source == NULL || pattern == NULL ){
return -1;
}
int * next = (int *)malloc( sizeof(int) * patternLength );
cal_next_array(patternLength,pattern,next);
int k = -1;
for ( int i = 0 ; i < sourceLength; i ++) {
while ( k > -1 && pattern[k+1] != source[i] ) {
k = next[k];
}
if( pattern[k+1] == source[i]){
k ++;
}
if( k == patternLength - 1){
delete next;
return i - patternLength + 1;
}
}
delete next;
return -1;
}

int main(){
char source[] = "abcaabcab";
char pattern[] = "abcab";
cout << kmp(source, pattern, sizeof(source) -1 , sizeof(pattern) -1 )<<endl;
return 1;
}