usaco1.1.4 Broken Necklace破碎的项链

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usaco1.1.4 beads

Broken Necklace破碎的项链

仍然是模拟，但要注意这个项链是环状的。有一种比较先进的办法是把这个项链载入两次，这样就可以从头到尾遍历了。注意白色的珠子不能作为起点。
我的程序没有用上面的方法，直接遍历到最后在返回开头。

/*ID: wsc5001LANG: CTASK: beads*/#include<stdio.h>#include <stdlib.h>char ch[351];int n;int zhaoqian(int st){    char goon;    int i=0,timess=0;    while(st+i<n && (ch[st+i]=='w') )        {i++;}    while(st+i>=n && (ch[st+i-n]=='w'))        {i++;}    goon = ch[st+i];    i=0;    while(st+i<n && (ch[st+i]==goon||ch[st+i]=='w'))        {timess++; i++;}    while(st+i>=n && (ch[st+i-n]==goon||ch[st+i-n]=='w'))        {timess++; i++;}    return timess;}int zhaohou(int st){    char goon;    int i=0,timess=0;    while(st-i>=0 && (ch[st-i]=='w'))    {i++;}    while(st-i<0 && (ch[st-i+n]=='w'))    {i++;}    goon = ch[st-i];    i=0;    while( st-i>=0 && (ch[st-i]==goon||ch[st-i]=='w') )        {timess++; i++;}    while(st-i<0 && (ch[st-i+n]==goon||ch[st-i+n]=='w'))        {timess++; i++;}    return timess;}int main(){    FILE *fin,*fout;    fin=fopen("beads.in","r");    fout=fopen("beads.out","w");    int nfront=0,nback=0,max=0;    int i,j,flag;    //读入     fscanf(fin,"%d%s",&n,ch);    flag=0;    for (i=0;i<n;i++)        if(ch[i]!=ch[0]&&ch[i]!='w')        {flag=1;break;}    if (flag==0)    {fprintf(fout,"%d\n",n);}    else    {        for (i=0;i<n;i++)        {            nfront=zhaoqian(i+1);            nback=zhaohou(i);            if (nfront+nback>max)                max=nfront+nback;            if (max>n)                max=n;        }    fprintf(fout,"%d\n",max);    }    fclose(fin);    fclose(fout);    //system("pause");}