一个更安全的kmp，处理m=1的情况

Algorithms/String/KMP.cpp

@@ -1,87 +1,56 @@
-/*#include <cstdio>
-#include <cstring>
-char s[100000], p[100000];
-int next[100000];
-void getNext(char* P)
-{
-    int lenP = strlen(P);
-    next[0] = -1;
-    int k = -1, i = 0;
-    while (i < lenP - 1)
-        if (k == -1 || P[k] == P[i])
-            i++, k++, next[i] = (p[i] == p[k]) ? next[k] : k;
-        else k = next[k];
-}
-int match(char* S, char* P)
-{
-    int lenS = strlen(S), lenP = strlen(P), i = 0, j = 0;
-    while (i < lenS && j < lenP)
-        if (j == -1 || S[i] == P[j])
-            i++, j++;
-        else
-            j = next[j];
-    return j == lenP ? i - j : -1;
-}
-int main()
-{
-    int n;
-    scanf("%d", &n);
-    for (int i = 0; i < n; i++)
-    {
-        scanf("%s%s", p, s);
-        getNext(p);
-        char* str = s;
-        int pos = match(str, p), ans = 0;
-        while (pos != -1)
-        {
-            ans++;
-            str += pos + 1;
-            pos = match(str, p);
-        }
-        printf("%d\n", ans);
-    }
-    return 0;
-}*/
 #include<cstdio>
 #include<cstring>
-using namespace std;
+
 const int mt = 1e6 + 5;
-char x[mt], y[mt], next[mt];
+
+char x[mt], y[mt];
 int m, n;
-void pre()
+
+template<typename T>
+int cnt(T *x, int m, T *y, int n)
 {
-    int i = 0, j = next[0] = -1;
-    while (i != m)
-    {
-        if (-1 == j || y[i] == y[j]) next[++i] = ++j;
-        else j = next[j];
-    }
+	if (m > n) return 0;
+	if (m == 1)
+	{
+		int ret = 0;
+		for (int i = 0; i < n; ++i)
+		{
+			if (y[i] == x[0]) ++ret;
+		}
+		return ret;
+	}
+	T *next = new T[n]();
+	int i = 0;
+	int j = next[0] = -1;
+	while (i < m)
+	{
+		if (-1 == j or y[i] == y[j]) next[++i] = ++j;
+		else j = next[j];
+	}
+	i = 0;
+	j = 0;
+	int ans = 0;
+	while (i < n and j < m)
+	{
+		if (-1 == j or y[i] == x[j]) ++i, ++j;
+		else j = next[j];
+		if (j == m)
+			++ans, i -= j - 1, j = -1;
+	}
+	delete next;
+	return ans;
 }
-int cnt()
+
+
+int main(const int argc, const char *argv[])
 {
-    pre();
-    int i = 0, j = 0, ans = 0;
-    while (i != n && j != m)
-    {
-        if (-1 == j || y[i] == x[j]) i++, j++;
-        else j = next[j];
-        if (j == m)
-            ans++, i -= j - 1, j = -1;
-    }
-    return ans;
+	int t;
+	scanf("%d", &t);
+	while (t --> 0)
+	{
+		scanf("%s", y);
+		scanf("%s", x);
+		printf("%d\n", cnt(x, strlen(x), y, strlen(y)));
+	}
+	return 0;
 }
-int main()
-{
-    int t;
-    scanf("%d", &t);
-    while (t--)
-    {
-        scanf("%s", x);
-        scanf("%s", y);
-        m = strlen(x), n = strlen(y);
-        //cout<<m<<endl<<n<<endl;
-        //cout<<x<<endl<<y<<endl;
-        printf("%d\n", cnt());
-    }
-    return 0;
-}