1255 - Substring Frequency
InputA string is a finite sequence of symbols that are chosen from an alphabet. In this problem you are given two non-empty strings A and B, both contain lower case English alphabets. You have to find the number of times B occurs as a substring of A.
Input starts with an integer T (≤ 5), denoting the number of test cases.
Each case starts with two lines. First line contains A and second line contains B. You can assume than 1 ≤ length(A), length(B) ≤ 106.
Output
For each case, print the case number and the number of times B occurs as a substring of A.
Sample Input |
Output for Sample Input |
4axbyczdabcabcabcabcabc
abc aabacbaabbaaz aab aaaaaa aa |
Case 1: 0Case 2: 4Case 3: 2Case 4: 5 |
Note
Dataset is huge, use faster I/O methods.
题目类型:KMP
算法分析:这是一道使用KMP算法求解模式串在目标串中数量的题目,思路是如果模式串匹配成功,则将模式串指针j回溯至Next[j],看看能不能再一次匹配
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 |
#include <set> #include <bitset> #include <list> #include <map> #include <stack> #include <queue> #include <deque> #include <string> #include <vector> #include <ios> #include <iostream> #include <fstream> #include <sstream> #include <iomanip> #include <algorithm> #include <utility> #include <complex> #include <numeric> #include <functional> #include <cmath> #include <ctime> #include <climits> #include <cstdarg> #include <cstdio> #include <cstdlib> #include <cstring> #include <cctype> #include <cassert> #define lson rt << 1, l, m #define rson rt << 1 | 1, m + 1, r using namespace std; const int INF = 0x7FFFFFFF; const double EPS = 1e-10; const double PI = 2 * acos (0.0); const int MOD = 7; const int maxn = 1000000 + 66; char pattern[maxn], target[maxn]; int suffix[maxn]; void Build () { int len = strlen (pattern); suffix[0] = -1; suffix[1] = 0; int k = 0; int i; for (i = 2; i <= len; i++) { while (k >= 0 && pattern[i-1] != pattern[k]) k = suffix[k]; suffix[i] = ++k; } } int KMP () { int len_pattern = strlen (pattern); int len_target = strlen (target); int cnt = 0; int i = 0, j = 0; while (i < len_target) { if (pattern[j] == target[i] || j == -1) { i++; j++; } else j = suffix[j]; if (j == len_pattern) { cnt++; j = suffix[j]; } } return cnt; } |