解题报告不写了，光贴个代码。。主要是注意各个符号，，然后字符串的变换等等。
;INF = 0x3f3f3f3f;maxn = 210;char num[maxn];char a[maxn], b[maxn];int n, B;inline int getnum(char &a){if(a >= ‘0’ && a <= ‘9’) return a-‘0’;else return a-‘a’+10;}inline char cal(char &a, char &b){int t1 = getnum(a);int t2 = getnum(b);t1 = (t1 + t2) % B;if(t1 < 10) return t1+’0′;else return t1-10+’a’;}trans(char *a){int len = strlen(a);// printf(“%d”, len);for(int i = 0; i < len/2; i++)swap(a[i], a[len-i-1]);}inline void add(char *a, char *b){int len1 = strlen(a);int len2 = strlen(b);int len, rest;if(len1 > len2){len = len2;rest = len1;}else{len = len1;rest = len2;}for(int i = 0; i < len; i++)a[i] = cal(a[i], b[i]);if(rest == len1) return;else for(int i = len; i < len2; i++) a[i] = b[i];}int main(){#ifdef DEBUGfreopen(“input”, “r”, stdin);#endifint len;while(scanf(“%d%d”, &n, &B)!= EOF){memset(num, 0, sizeof(num));for(int i = 0; i <n ;i++){scanf(“%s”, a);trans(a); add(num, a);}trans(num);len = strlen(num);int i;for(i = 0; i < len; i++)if(num[i] != ‘0’) break;if(i == len)printf(“0”);else for(;i < len; i++)printf(“%c”, num[i]);printf(“\n”);}return 0;}
如果雨后还是雨，如果忧伤过后还是忧伤，
