« Find indices of all occurrence of one string in other

Input :

GeeksforGeeks

Geeks

Output : 0 8

Input :

GFG

g

Output : NONE

Copy
1#include<iostream>
2#include<iomanip>
3#include<algorithm>
4#include<string>
5#include<cstring>
6#include<vector>
7#include<cmath>
8#include <map>
9#include<climits>
10//climits for INT_MIN
11#include <unordered_map>
12using namespace std;
13
14void computeLPSArray(string pat, int M, int* lps)
15{
16    int len = 0;
17    lps[0] = 0; // lps[0] is always 0
18
19    int i = 1;
20    while (i < M) {
21        if (pat[i] == pat[len]) {
22            len++;
23            lps[i] = len;
24            i++;
25        }else if (pat[i] != pat[len]){
26            if (len != 0) {
27                len = lps[len - 1];
28            }else if(len == 0){
29                lps[i] = 0;
30                i++;
31            }
32        }
33    }
34}
35
36void KMPSearch(string pat, string txt){
37    int M = pat.length();
38    int N = txt.length();
39
40    int lps[M];
41
42    computeLPSArray(pat, M, lps);
43
44    int i = 0;
45    int j = 0;
46    while ((N - i) >= (M - j)) {
47        if (pat[j] == txt[i]) {
48            j++;
49            i++;
50        }
51
52        if (j == M) {
53            printf("Found pattern at index %d ", i - j);
54            j = lps[j - 1];
55        }else if (i < N && pat[j] != txt[i]) {
56            // Do not match lps[0..lps[j-1]] characters,
57            // they will match anyway
58            if (j != 0){
59                j = lps[j - 1];
60            }else{
61                i = i + 1;
62            }
63
64        }
65    }
66}
67
68int main()
69{
70    string txt = "AABAACAADAABAABA";
71    string pat = "AABA";
72    KMPSearch(pat, txt);
73    return 0;
74}