Create Shortest Common Supersequence - DP.cpp

Author: nikolatechie

Shortest Common Supersequence - DP.cpp

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+// Dynamic programming solution
+#include <bits/stdc++.h>
+#include <ext/rope>
+using namespace std;
+using namespace __gnu_cxx;
+
+using ld = long double;
+using llint = long long;
+using ullint = unsigned long long;
+using pii = pair <int,int>;
+using pcc = pair <char,char>;
+using pss = pair <string,string>;
+using vi = vector <int>;
+using vb = vector <bool>;
+using vii = vi::iterator;
+
+#define INF (1<<30)
+#define MOD 1000000007
+#define mp make_pair
+#define mt make_tuple
+#define all(c) c.begin(), c.end()
+#define ms(name,val) memset(name, val, sizeof name)
+#define np nullptr
+
+
+int main()
+{
+    ios_base::sync_with_stdio(0);
+    //cin.tie(0);
+
+    string a, b;
+    cin >> a >> b;
+    int n = a.size(), m = b.size();
+    vector <vi> DP(n+1, vi(m+1, 0));
+
+    for (int t1 = 0; t1 <= n; ++t1)
+    {
+        for (int t2 = 0; t2 <= m; ++t2)
+        {
+            if (!t1)
+                DP[t1][t2] = t2;
+            else if (!t2)
+                DP[t1][t2] = t1;
+            else if (a[t1-1] == b[t2-1])
+                DP[t1][t2] = 1 + DP[t1-1][t2-1];
+            else
+                DP[t1][t2] = 1 + min(DP[t1-1][t2], DP[t1][t2-1]);
+        }
+    }
+
+    cout << "\nShortest common supersequence:\n";
+    cout << "Length: " << DP[n][m] << '\n';
+    cout << "Sequence: ";
+    string seq;
+    int x = n, y = m;
+
+    while (x && y)
+    {
+        if (a[x-1] == b[y-1])
+        {
+            seq.push_back(b[y-1]);
+            --x, --y;
+        }
+        else if (DP[x-1][y] < DP[x][y-1])
+        {
+            seq.push_back(a[x-1]);
+            --x;
+        }
+        else
+        {
+            seq.push_back(b[y-1]);
+            --y;
+        }
+    }
+
+    while (x)
+    {
+        seq.push_back(a[x-1]);
+        --x;
+    }
+
+    while (y)
+    {
+        seq.push_back(b[y-1]);
+        --y;
+    }
+
+    reverse(all(seq));
+    cout << seq << '\n';
+
+
+
+    return 0;
+}