126 lines
4.5 KiB
C++
126 lines
4.5 KiB
C++
#include <cstdio>
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#include <ctype.h>
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#include <cmath>
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#include <stdlib.h>
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char rin[10100],rout[10100];
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struct sta{
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double x;
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bool digit;
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char ch;
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} stack[10100];
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double tst[10100];
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int top,ttop,rtop;
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int priority(char ch)
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{
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switch (ch)
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{
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case '+' :
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case '-' : return 1;break;
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case '*' :
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case '/' : return 2;break;
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case '^' : return 3;break;
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}
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}
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int main()
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{
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int i;
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bool mark;
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while (scanf("%s",rin) != EOF)
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{
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mark = true;
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top = 0; i = 0; rtop = 0;
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while (rin[i])
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{
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if (mark)
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{
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mark = false;
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while (rin[i] == '(')
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{
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i ++;
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rout[++rtop] = '(';
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}
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if (rin[i] == '-' || rin[i] == '+')
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{
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stack[++top].x = 0;
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stack[top].digit = true;
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}
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else {
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sscanf(&rin[i],"%lf",&stack[++top].x);
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stack[top].digit = true;
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while (!isdigit(rin[i]))
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i++;
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while (isdigit(rin[i]) || rin[i] == '.')
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i++;
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}
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}
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else {
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mark = true;
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if (rin[i] == ')')
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{
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while (rout[rtop] != '(')
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{
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stack[++top].ch = rout[rtop--];
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stack[top].digit = false;
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}
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rtop--;
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mark = false;
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}
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else {
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if (!rtop || rout[rtop] == '(')
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rout[++rtop] = rin[i];
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else {
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while ( rtop&& priority(rin[i]) < priority(rout[rtop]))
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{
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stack[++top].ch = rout[rtop--];
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stack[top].digit = false;
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}
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if (rtop && priority(rin[i]) == priority(rout[rtop]))
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{
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stack[++top].ch = rout[rtop];
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stack[top].digit = false;
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rout[rtop] = rin[i];
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}
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else rout[++rtop] = rin[i];
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}
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}
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i ++;
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}
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}
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while (rtop)
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{
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stack[++top].ch = rout[rtop--];
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stack[top].digit = false;
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}
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ttop = 0; i = 1;
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bool flag = true;
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while (i <= top && flag)
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{
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if (stack[i].digit)
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tst[++ttop] = stack[i].x;
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else {
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double b = tst[ttop--], a = tst[ttop];
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switch (stack[i].ch)
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{
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case '+': tst[ttop] = a + b;
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break;
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case '-': tst[ttop] = a - b;
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break;
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case '*': tst[ttop] = a * b;
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break;
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case '/': if (fabs(b) < 0.00000001)
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flag = false;
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else tst[ttop] = a / b;
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break;
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case '^': tst[ttop] = pow(a,b);
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break;
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}
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}
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i++;
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}
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if (flag)
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printf("%.8lf\n",tst[ttop]);
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else printf("The teacher is so lazy!\n");
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}
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return 0;
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}
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