Longest Common Subsequence in C++.

Author: ezaznitd

LCS.cpp

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+#include<bits/stdc++.h>
+#include<string.h>
+using namespace std;
+//This function will return longest common subsequence of two given string;
+int LCS(char str1[], char str2[], int n, int m)
+{
+	vector<char>vec;
+	int L[n+1][m+1];		//initialize a 2D array;
+	int i,j;
+	for(i=0;i<=n;i++)
+	{
+		for(j=0;j<=m;j++)
+		{
+			if(i==0 || j==0)
+				L[i][j]=0;
+			else if(str1[i-1]==str2[j-1]) 	//if 'i'th character of 1st string equal to 'j'th character of
+			{								//2nd string then push that character to the vector and go for
+				L[i][j]=1+L[i-1][j-1];		//next character of both string;
+				vec.push_back(str1[i-1]);
+			}
+			else							//else return max of 'i-1' characters of 1st string and j characters
+				L[i][j]=max(L[i-1][j],L[i][j-1]);	//and 'i' characters of 1st string and 'j-1' characters of
+		}											//2nd sgtring;
+	}
+	int c=L[n][m];
+	cout << "\nLargest Common Subsequence is: ";
+	for(int i=vec.size()-c;i<vec.size();i++)	//print longest common subsequence;
+		cout << vec[i];
+	cout << endl;
+	return L[n][m]; 	//return length of longest common subsequence;
+}
+int main()
+{
+	char str1[100],str2[100];
+	cout << "Enter the two string: " << endl;
+	cin>>str1>>str2;	//enter two string;
+	int n=strlen(str1);	//length of first string;
+	int m=strlen(str2);	//length of second string;
+	cout << "Length of Largest Common Subsequence: " << LCS(str1, str2, n, m);	//print LCS of two string;
+	return 0;
+}