Finding Longest Common Subsequence in C

LCS.c

#include<stdio.h>
#include<string.h>

int max(int a, int b);
void findLCS(char X[], char Y[], int XLen, int YLen);

int max(int a, int b) {
  return (a > b)? a : b;
}

void findLCS(char X[], char Y[], int XLen, int YLen) {
  int L[XLen + 1][YLen + 1];
  int r, c, i;
  /*
   * find the length of the LCS
   */
  for(r = 0; r <= XLen; r++) {
    for(c = 0; c <= YLen; c++) {
      if(r == 0 || c == 0) {
        L[r][c] = 0;
      } 
      else if(X[r - 1] == Y[c - 1]) {
        L[r][c] = L[r - 1][c - 1] + 1;
      } 
      else {
        L[r][c] = max(L[r - 1][c], L[r][c - 1]);
      }
    }
  }
  /*
   * Print LCS
   */
  r = XLen;
  c = YLen;
  i = L[r][c];
  char LCS[i+1];          // Creating a char type array of size L[r][c]+1
  /*
   * setting the NULL character at the end of LCS character array.
   * as we know in C programming language, NULL character is used
   * to denote the end of a string
   */
  LCS[i] = '\0';
  while(r > 0 && c > 0) {
    if(X[r - 1] == Y[c - 1]) {
      LCS[i - 1] = X[r - 1];
      i--;
      r--;
      c--;
    } 
    else if(L[r - 1][c] > L[r][c - 1]) {
      r--;
    } 
    else {
      c--;
    }
  }
  //print result
  printf("LCS: %s\n", LCS);
  printf("Length of the LCS: %d\n", L[XLen][YLen]);
  
}


int main(void) {
  char X[50];
  char Y[50];
  printf("Enter String 1 : ");
  scanf("%s",X);
  printf("Enter String 2 : ");
  scanf("%s",Y);
  int XLen = strlen(X);
  int YLen = strlen(Y);
  findLCS(X, Y, XLen, YLen);
  return 0;
}

// References : https://www.youtube.com/watch?v=cfCdtJSu5pc