USACO 1.3.3 Calf Flac (calfflac)

1、比较愚蠢的暴力搜索：两个指针分别从从第一个和最后一个开始，循环往中间移动，判断两个指针之间的字符串是否是回文数。重复搜索过多，导致最后一个测试数据超时:(

/*ID: gengjia1LANG: CTASK: calfflac*/#include <stdio.h>#include <stdlib.h>#include <string.h>#include <ctype.h>//#define NDEBUG#include <assert.h>#define MAX_LEN 20000int count;struct str{int len;char s[MAX_LEN + 1];};struct pal{int len;int begin;int end;};int letter(const char a){if((a >= 'a' && a <= 'z') ||(a >= 'A' && a <= 'Z'))return 1;return 0;}int main(void) {FILE *fin = fopen ("calfflac.in", "r");FILE *fout = fopen ("calfflac.out", "w");assert(fin != NULL && fout != NULL);struct str s = {0};struct pal pa = {0};char tmp[80] = {0};char t[MAX_LEN] = {0};int curlen = 0;int i, j, k, p, q;while( fgets (tmp, 80, fin) != NULL){strcat(s.s, tmp);}s.len = strlen(s.s);for(i = 0; i < s.len; i++){if(letter(s.s[i]) == 0)continue;for(j = s.len-1; j > i; j--){if(letter(s.s[j]) == 0)continue;curlen = 0;for(p = i, q = j; p < q; ){if(letter(s.s[p]) == 0){p++;continue;}if(letter(s.s[q]) == 0){q--;continue;}if(tolower(s.s[p]) == tolower(s.s[q])){curlen += 2;p++;q--;}else{curlen = 0;break;}}if(p == q && letter(s.s[p]) == 1)curlen += 1;if(curlen > pa.len){pa.len = curlen;pa.begin = i;pa.end = j;}}}fprintf(fout, "%d/n", pa.len);for(i = pa.begin; i <= pa.end; i++){fprintf(fout, "%c", s.s[i]);}fprintf(fout, "/n");fclose(fin);fclose(fout);exit(0);}