Create KMP Search.cpp

Author: nikolatechie

KMP Search.cpp

@@ -0,0 +1,85 @@
+// KMP algorithm for pattern searching in O(n+m)
+#include <bits/stdc++.h>
+#include <ext/rope>
+using namespace std;
+using namespace __gnu_cxx;
+
+using ci = const int;
+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 n, m;
+string t, p;
+vi tmp;
+
+void buildArray()
+{
+    tmp.resize(m);
+    int i = 0, j = 1;
+
+    while (j < m)
+    {
+        while (i > 0 && p[i] != p[j])
+            i = tmp[i-1];
+
+        if (p[i] == p[j])
+        {
+            tmp[j] = i+1;
+            ++i, ++j;
+        }
+        else ++j;
+    }
+}
+
+void KMP_Search()
+{
+    int i = 0, j = 0;
+
+    while (i < n)
+    {
+        while (j > 0 && t[i] != p[j])
+            j = tmp[j-1];
+
+        if (t[i] == p[j])
+        {
+            ++i;
+            ++j;
+
+            if (j == m)
+                cout << i-m << '\n';
+        }
+        else ++i;
+    }
+}
+
+int main()
+{
+    ios_base::sync_with_stdio(0);
+    //cin.tie(0);
+
+    cin >> t >> p;
+    n = t.size();
+    m = p.size();
+    buildArray();
+    KMP_Search();
+
+
+
+    return 0;
+}