uva 537

来源：互联网发布：知彼定位编辑：程序博客网时间：2024/04/28 04:47

一道关于字符串的简单题，主要就是从字符串中找到两个等号的位置后，进行分析便可。

另外注意前缀所代表的数值大小(k, M, m)

#include <iostream>#include <stdlib.h>#include <stdio.h>#include <string>#include <sstream>using namespace std;int kasenum;string str;double power, volt, curr;int pos[3];char ch;double scan(int index){bool flag = false;double res = 0.0, frac = 0.0, ratio = 0.1, multi = 1;if ('-' == str[index])flag = true;else if (str[index] >= '0' && str[index] <= '9')res = str[index] - '0';index++;while (str[index] >= '0' && str[index] <= '9'){res = res * 10 + str[index] - '0';index++;}if ('.' == str[index]){index++;while (str[index] >= '0' && str[index] <= '9'){frac = frac + ratio * (str[index] - '0');index++;ratio *= 0.1;}}res += frac;switch (str[index]){case 'm':multi = 1e-3;break;case 'k':multi = 1e+3;break;case 'M':multi = 1e+6;break;default:multi = 1.0;break;}res *= multi;return flag ? -res : res;}void readInfo(){getline(cin, str);pos[0] = str.find('=');pos[1] = str.find('=', pos[0] + 1);for (int i = 0; i < 2; i++){switch (str[pos[i] - 1]){case 'U':volt = scan(pos[i] + 1);break;case 'I':curr = scan(pos[i] + 1);break;case 'P':power = scan(pos[i] + 1);break;}}}int main(){freopen("in.txt", "r", stdin);freopen("out.txt", "w", stdout);scanf("%d", &kasenum);getchar();int kase = 0;while (kasenum--){power = -1;volt = -1;curr = -1;readInfo();printf("Problem #%d\n", ++kase);if (-1 == power)printf("P=%.2lfW\n", volt * curr);else if (-1 == volt)printf("U=%.2lfV\n", power / curr);elseprintf("I=%.2lfA\n", power / volt);printf("\n");}return 0;}

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