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AC finally,时间很奇怪,第一次0ms,第二次16ms#include <string> #include <memory.h> using namespace std; void computeExp(); void ComputePowResult(char* a,int b,char*); #define MAX 200 #define BASEBITS 6 int main() { computeExp(); return 0; } void computeExp() { char base[BASEBITS]; int power; memset(base,0,sizeof(base)); while(scanf("%s%d",base,&power)==2) { if(power==0) { printf("1\n"); } else { char result[MAX]; ComputePowResult(base,power,result); } } } void ComputePowResult(char* base,int power,char *result) { string mytemp(base); int dotPos = mytemp.find('.'); int i,j; //如果有小数点 if(dotPos!=-1) { i = mytemp.length()-1; for(;i>0;i--) { //取出低位尾部0 if(mytemp[i]=='0') { mytemp.erase(i,1); } else { break; } } //remove the dot if(mytemp[i]=='.') { mytemp.erase(i,1); //没有小数 dotPos = 0; } else { mytemp.erase(dotPos,1); dotPos = i-dotPos; } } else { dotPos = 0; } int strLen = mytemp.length(); for(i=0;i<strLen;++i) { //去除高位前导0 if(mytemp[i]=='0') { mytemp.erase(i,1); --i; } else { break; } } //base==0 if(mytemp=="") { printf("0\n"); return; } char tempmul[MAX]; memset(result,0,MAX); memset(tempmul,0,sizeof(tempmul)); //反转,是数字从低位到高位排列,100->001,最后结果也是如此排列 for(i=mytemp.length()-1,j=0;i>=0;i--) { base[j] = result[j]=mytemp[i]-'0'; j++; } //转换后的幂底的总位数 int bits = mytemp.length(); //记录第i次乘法后的结果的位数 int totalbits = bits; for(i=0;i<power-1;i++) { //第i次乘法 memset(tempmul,0,sizeof(tempmul)); //幂底(即每次乘法的乘数)的位数 int kbit; for(kbit=0;kbit<bits;++kbit) { //乘数的每位都要乘以被乘数的所有位,然后将结果对应相加 j=0; while(j<totalbits) { int mul = base[kbit]*result[j]+tempmul[j+kbit]; tempmul[j+kbit+1] += mul/10; tempmul[j+kbit]=mul%10; j++; } } //此次乘法结果位数 totalbits=totalbits+bits; memcpy(result,tempmul,totalbits); //判断是否有进位,没有则总位数减1 if(result[totalbits-1]==0) totalbits --; } //统计低位的0,由于计算前已经将前后0去除,因此高位不会再有0 int low=0; //00000lowXXXX for(low=0;low<totalbits;low++) { if(result[low]!=0) { break; } } int high=totalbits-1; dotPos = dotPos*power-1; //输出整数,没有整数则不会输出 for(i=high;i>dotPos;i--) { printf("%d",result[i]); } //判断是否有小数,输出小数点 if(dotPos>=low) { printf("."); } //输出小数,没有则不会输出 for(i=dotPos;i>=low;i--) { printf("%d",result[i]); } printf("\n"); } Followed by: Post your reply here: |
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