UVA12467Secret Word（KMP）

#include<stdio.h>
#include<string.h>
char c1[1000011],c2[1000011];
int next[1000011];
int kmp()
{
    int k = strlen(c1),i,j,y = -1;
    memset(next,0,sizeof(next));
    next[0] = -1;
    for(i = 1; i < k ;i ++)
    {
        while(y>-1&&c1[i]!=c1[y+1])
            y = next[y];
        if(c1[y+1]==c1[i])
            y++;
        next[i] = y;
    }
    int max = -1;
    y = -1;
    for(i = 0 ; i < k ; i++)
    {
        while(y>-1&&c2[i]!=c1[y+1])
        y = next[y];
        if(c1[y+1]==c2[i])
        {
            y++;
            if(max<y)
            max = y;
        }
    }
    return max;
}
int main()
{
    int t,n,m,i,j,k;
    scanf("%d%*c", &t);
    while(t--)
    {
        gets(c1);
        k = strlen(c1);
        for(i =0 ;i <= k-1 ;i++)
        {
            c2[i] = c1[k-i-1];
        }
        n = kmp();
        for(i = n ; i >= 0 ; i--)
            printf("%c", c1[i]);
        puts("");
    }
    return 0;
}