C语言编程题——密码截取

Catcher是MCA国的情报员，他工作时发现敌国会用一些对称的密码进行通信，比如像这些ABBAABA，A，123321，但是他们有时会在开始或结束时加入一些无关的字符以防止别国破解。比如进行下列变化ABBA->12ABBA,ABA->ABAKK,123321->51233214　。因为截获的串太长了，而且存在多种可能的情况（abaaab可看作是aba,或baaab的加密形式）.本题含有多组样例输入。
输入描述:
输入一个字符串
输出描述:
返回有效密码串的最大长度
输入
ABBA
输出
4

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<string.h>
#include<windows.h>
int StrPassWord(char *p,int len){
    
    
	int pass = 0;
	int i, j;
	for (i = 0; i < len;++i){
    
    
		for (j = i + 1; j < len&&*(p+i)!=*(p+j);++j){
    
    }
		int start = i+1;
		int end = j-1;
		int flag = 1;
		while (end>start&&flag!=0){
    
    
			if (*(p+start)!=*(p+end)){
    
    
				flag = 0;
			}
			end--;
			start++;
		}
		if (j == len&&*(p + i) != *(p + j)){
    
    }
		else{
    
    
			if (flag==1&&pass < j - i + 1){
    
    
				pass = j - i + 1;
			}
		}
	}
	return pass;
}
int main(){
    
    
	char str[50000];
	scanf("%s",str);
	printf("%d\n",StrPassWord(str,strlen(str)));
	system("pause");
	return 0;
}

输入：
dsuehgfqxzrnkmtmiwytshrerjfybxirufrsobkjeghiunftxyqqcyoreevvktxgvjjqzvcujsynsrlgllebyukyxgugrvkesovfhzdznstvtbblmjcngwsdrmfczsihiblqhkfvhzylwopepfmnixeesvugyifdxvpcknpqunolpgjehoxgylnzoggqpbdkhrngchidhfdktblrifjvppttemmplzrsbjhltvwprhkigkvfkxcxfsgyiyuuziqurgcmddqshenindtrfzlrqpfpekfosmugpwjgydtbwexcwrvdedposftffjrfeojsqpxtoguroojsgrwpyiyhurprcfsgnnykjtrjjzdswfqfwuohpcssgjzyikruvomeggqzyslmfurgnmhyvnksktvdcidvutrrxzixbxiypbvozgnmopfjiljggqrronwkfqvlpdwhtzfpsokfbvftyxdinknsrjlxbzyfmsinegprbnuezqlikgsbbixfdjtsjxojqwxdrvwfflrwjsnpcxqvfpmbidyvvlcnvvvvbglhhmkpuzhosfitgzclicpzsvozsbtvtlmjffqieosliqysgyxmceytmezfbtkcprfomftlkyortyfmykslfdmxzfeetmzxbuvoorpwmkerujcjcuuyvmpqidrrksrtmxhqoqdyvjgvcftbhywmbdfoixecfgorpxoxbqlhbnynwflbodsdqvwwoizdfyczefvonoczocvtbixehcvpmimyxgzddvomklofuthtytqougojqwmxvhzpmvtfsjwrgmxuoeizmnfptssolqbmnrhfjitoqxizflyoddgjlxknumclfmpmrzpomrqqogvmwgclpquhuqbkriyjkwcusetkyxozomcrsuyfmsddwubkiyyjoeqlzjsfnwkhdpgxkeicbivlwbdvcbvdqbyxuwdolmtxzgpogtzctlcjemoxdrbrmmtkuuidtiebckmqluiszgichpmgbsxdiurxdgkvvufyihcjejgwwepswxmjducltnxngtylgiqcvxldeebykysdgwokcupxmjnbiqlzovnocuesodotqivceqhimuhtromxxullejgzhzevzvtdhbfhcwbdivgslkfmudzofbmeeqixuprbsyrelcgvvkbtkgckezrrisnnkwwchcfwlqdoucccqinjplgwlqcylqojstlvdjmcjyqjsqwrvxjmujcuzirinocnnwszxjnyszncytltbusmcsxustpxeuxgmwlixnjnigsxnollfbpqrwohbshbohhnpsvenvgreqfwqypkkibenvgjcwmumwcgehehiyediindvppefciihjkcnzvelorusllpbexivekbflpyqpefpjlumctorwejnefenhrlfugnkywvwuvrdrxsxjksgowxholmpjfyjcksmhwpcpjcodwzmolzgkcjxmiqxdpewlyjilcbbwyxmxhqvsxkepiwdvmfxdceiswscupzpmhvmyciyosxuwnmjxnkdhhnquxsmekmcwgcklxzhhqxkebqcvxpsqzuoxikverbskrwvewomemysgcmrdnzgufysnoxuerrqcufevwwumrvbowvvkjuediygphwgwgdrpbgreytkmgcmzonbyxwkolywjcigvyqqhwsjmtkvvhbtuhctcigvfnkkffvsjrjiumlowlwvsbuopmsfcqrxlpprtmswlkdmkoxewhtfkzzoohdbutqccmzsscjdozeeecdqmugcrqqfjingovwfmvnltdfcmrofcftnoozquguyyzdxqqgwbdpotbquhokorykpurvwbvcwdnmzgimuzjipikdtvhstsgeykmunxvbszjmbgwhiymumfmlhennthtjwspxvqrelkhwqxjrzbkqbobfetlejvdhzpmwreqfhnupgovixdemmngzorgfooiruhjbjmvwgmzrvjgrwouxugmysbrdtdujjeffomribgqkhjohitgonqevcweedmleexqjgtywpwbwmoltxbdkiyvgrykhbesgckhvecyvcjryqbhstwrcloqmoivrmkkimzwbywumxfrzyterxmwpqcullcvebkflwmbbexqifohjrrgsnbsqhlxkwkuhwocmjfrhyfkqpqlbvxokbvbufqffclzlnlszcimzucrsrohldxeohdiktubdrvkzvgvhnrkeenmhcvujlxlpcyhohumnuxmswwfwyhuyqhurvcrvmnkgsyygunrvpbvdmpetuixhwtnswhmgtuunzybkyosezpzttrzcdukbtmxxeschlkjgqgrnhvixqbcusimvwdceedhhbbbrxefvztdcfdtzglhmzfthlmc
输出：7