Add wildcard pattern matching (#2441)
This commit is contained in:
Nikita Kapoor
GitHub
parent
7cc96f9a15
commit
05c65c1e4c
171
DynamicProgramming/RegexMatching.java
Normal file
171
DynamicProgramming/RegexMatching.java
Normal file
@ -0,0 +1,171 @@
|
||||
package DynamicProgramming;
|
||||
|
||||
/**
|
||||
* Given a text and wildcard pattern implement a wildcard pattern matching
|
||||
* algorithm that finds if wildcard is matched with text. The matching should
|
||||
* cover the entire text
|
||||
* ?-> matches single characters
|
||||
* *-> match the sequence of characters
|
||||
**/
|
||||
|
||||
/**
|
||||
* For calculation Time and Space Complexity. Let N be length of src and M be length of pat
|
||||
**/
|
||||
|
||||
public class RegexMatching {
|
||||
|
||||
// Method 1: Using Recursion
|
||||
// Time Complexity=0(2^(N+M)) Space Complexity=Recursion Extra Space
|
||||
static boolean regexRecursion(String src, String pat) {
|
||||
if (src.length() == 0 && pat.length() == 0) {
|
||||
return true;
|
||||
}
|
||||
if (src.length() != 0 && pat.length() == 0) {
|
||||
return false;
|
||||
}
|
||||
if (src.length() == 0 && pat.length() != 0) {
|
||||
for (int i = 0; i < pat.length(); i++) {
|
||||
if (pat.charAt(i) != '*') {
|
||||
return false;
|
||||
}
|
||||
}
|
||||
return true;
|
||||
}
|
||||
char chs = src.charAt(0);
|
||||
char chp = pat.charAt(0);
|
||||
|
||||
String ros = src.substring(1);
|
||||
String rop = pat.substring(1);
|
||||
|
||||
boolean ans;
|
||||
if (chs == chp || chp == '?') {
|
||||
ans = regexRecursion(ros, rop);
|
||||
} else if (chp == '*') {
|
||||
boolean blank = regexRecursion(src, rop);
|
||||
boolean multiple = regexRecursion(ros, pat);
|
||||
ans = blank || multiple;
|
||||
} else {
|
||||
ans = false;
|
||||
}
|
||||
return ans;
|
||||
}
|
||||
|
||||
// Method 2: Using Recursion and breaking string using virtual index
|
||||
// Time Complexity=0(2^(N+M)) Space Complexity=Recursion Extra Space
|
||||
static boolean regexRecursion(String src, String pat, int svidx, int pvidx) {
|
||||
if (src.length() == svidx && pat.length() == pvidx) {
|
||||
return true;
|
||||
}
|
||||
if (src.length() != svidx && pat.length() == pvidx) {
|
||||
return false;
|
||||
}
|
||||
if (src.length() == svidx && pat.length() != pvidx) {
|
||||
for (int i = pvidx; i < pat.length(); i++) {
|
||||
if (pat.charAt(i) != '*') {
|
||||
return false;
|
||||
}
|
||||
}
|
||||
return true;
|
||||
}
|
||||
char chs = src.charAt(svidx);
|
||||
char chp = pat.charAt(pvidx);
|
||||
|
||||
boolean ans;
|
||||
if (chs == chp || chp == '?') {
|
||||
ans = regexRecursion(src, pat, svidx + 1, pvidx + 1);
|
||||
} else if (chp == '*') {
|
||||
boolean blank = regexRecursion(src, pat, svidx, pvidx + 1);
|
||||
boolean multiple = regexRecursion(src, pat, svidx + 1, pvidx);
|
||||
ans = blank || multiple;
|
||||
} else {
|
||||
ans = false;
|
||||
}
|
||||
return ans;
|
||||
}
|
||||
|
||||
// Method 3: Top-Down DP(Memoization)
|
||||
// Time Complexity=0(N*M) Space Complexity=0(N*M)+Recursion Extra Space
|
||||
static boolean regexRecursion(String src, String pat, int svidx, int pvidx, int[][] strg) {
|
||||
if (src.length() == svidx && pat.length() == pvidx) {
|
||||
return true;
|
||||
}
|
||||
if (src.length() != svidx && pat.length() == pvidx) {
|
||||
return false;
|
||||
}
|
||||
if (src.length() == svidx && pat.length() != pvidx) {
|
||||
for (int i = pvidx; i < pat.length(); i++) {
|
||||
if (pat.charAt(i) != '*') {
|
||||
return false;
|
||||
}
|
||||
}
|
||||
return true;
|
||||
}
|
||||
if (strg[svidx][pvidx] != 0) {
|
||||
return strg[svidx][pvidx] == 1 ? false : true;
|
||||
}
|
||||
char chs = src.charAt(svidx);
|
||||
char chp = pat.charAt(pvidx);
|
||||
|
||||
boolean ans;
|
||||
if (chs == chp || chp == '?') {
|
||||
ans = regexRecursion(src, pat, svidx + 1, pvidx + 1, strg);
|
||||
} else if (chp == '*') {
|
||||
boolean blank = regexRecursion(src, pat, svidx, pvidx + 1, strg);
|
||||
boolean multiple = regexRecursion(src, pat, svidx + 1, pvidx, strg);
|
||||
ans = blank || multiple;
|
||||
} else {
|
||||
ans = false;
|
||||
}
|
||||
strg[svidx][pvidx] = ans == false ? 1 : 2;
|
||||
return ans;
|
||||
}
|
||||
|
||||
// Method 4: Bottom-Up DP(Tabulation)
|
||||
// Time Complexity=0(N*M) Space Complexity=0(N*M)
|
||||
static boolean regexBU(String src, String pat) {
|
||||
|
||||
boolean strg[][] = new boolean[src.length() + 1][pat.length() + 1];
|
||||
strg[src.length()][pat.length()] = true;
|
||||
for (int row = src.length(); row >= 0; row--) {
|
||||
for (int col = pat.length() - 1; col >= 0; col--) {
|
||||
if (row == src.length()) {
|
||||
if (pat.charAt(col) == '*') {
|
||||
strg[row][col] = strg[row][col + 1];
|
||||
} else {
|
||||
strg[row][col] = false;
|
||||
}
|
||||
} else {
|
||||
char chs = src.charAt(row);
|
||||
char chp = pat.charAt(col);
|
||||
|
||||
boolean ans;
|
||||
if (chs == chp || chp == '?') {
|
||||
ans = strg[row + 1][col + 1];
|
||||
} else if (chp == '*') {
|
||||
boolean blank = strg[row][col + 1];
|
||||
boolean multiple = strg[row + 1][col];
|
||||
ans = blank || multiple;
|
||||
} else {
|
||||
ans = false;
|
||||
}
|
||||
strg[row][col] = ans;
|
||||
}
|
||||
}
|
||||
}
|
||||
return strg[0][0];
|
||||
}
|
||||
|
||||
public static void main(String[] args) {
|
||||
|
||||
String src = "aa";
|
||||
String pat = "*";
|
||||
System.out.println("Method 1: "+regexRecursion(src, pat));
|
||||
System.out.println("Method 2: "+regexRecursion(src, pat, 0, 0));
|
||||
System.out.println("Method 3: "+regexRecursion(src, pat, 0, 0, new int[src.length()][pat.length()]));
|
||||
System.out.println("Method 4: "+regexBU(src, pat));
|
||||
|
||||
}
|
||||
|
||||
}
|
||||
// Memoization vs Tabulation : https://www.geeksforgeeks.org/tabulation-vs-memoization/
|
||||
// Question Link : https://practice.geeksforgeeks.org/problems/wildcard-pattern-matching/1
|
||||
Loading…
Reference in New Issue
Block a user