Sunday算法其实思想跟BM算法很相似，只不过Sunday算法是从前往后匹配，在匹配失败时关注的是文本串中参加匹配的最末位字符的下一位字符。如果该字符没有在匹配串中出现则直接跳过，即移动步长= 匹配串长度+ 1；否则，同BM算法一样其移动步长=匹配串中最右端的该字符到末尾的距离+1。

sunday.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int getIndex(char *tp, char ch) {
    if (tp == NULL || !ch)
        return -1;
    int tp_len = strlen(tp);
    for (int i = 0; i < tp_len; i++) {
        if (ch == tp[i]) {
            return tp_len - i - 1;
        }
    }
    return -1;
}

int sunday(char *source, char *target) {
    int m = strlen(source);
    int n = strlen(target);
    int i = 0, j = 0;
    int last = 0;

    while (i < m) {
        if (source[i] == target[j]) {
            printf("match %c;\n", source[i]);
            if (j == n - 1)
                return 1;
            i++;
            j++;
        } else {
            last = n + i - j;
            int offset_i = getIndex(target, source[last]);
            if (offset_i == -1) {
                i = last + 1;
                j = 0;
            } else {
                i = offset_i + 1;
                j = 0;
            }
        }
    }
    puts("match faild!");
    return 0;
}
int main(void) {
    char *c1 = "Hello,world!";
    char *c2 = "wo";
    sunday(c1, c2);
    return 0;
}