Uvs: 10700

Question: 10700-Camel trading

The expression is composed of numbers and plus signs. The value range is [1, 20 ]. These expressions may lack parentheses. Ask the maximum and minimum values that can be obtained after such expressions are added with parentheses.

Solution: because these numbers are all positive integers, you can use greed. Otherwise, we can see that the maximum value is the addition before multiplication, and the minimum value is the multiplication before addition. Note that the value here must be long because the value of the expression may exceed int.

Code:

#include <stdio.h>#include <string.h>const int N = 15;char op[N];char str[3 * N];long long num[N];long long caculate_max (int count) {long long temp[N];for (int i = 0; i < count; i++)temp[i] = num[i];for (int i = count - 2; i >= 0; i--)if (op[i] == '+') {temp[i] += temp[i + 1];temp[i + 1] = temp[i];}long long sum = temp[0];for (int i = 0; i < count - 1; i++) {if (op[i] == '*') sum *= temp[i + 1];}return sum;}long long caculate_min (int count) {long long temp[N];for (int i = 0; i < count; i++)temp[i] = num[i];for (int i = count - 2; i >= 0; i--) {if (op[i] == '*')temp[i] = temp[i] * temp[i + 1];}long long sum = temp[0];for (int i = 0; i <= count - 2; i++) {if (op[i] == '+')sum += temp[i + 1];}return sum;}int init () {int t = 0;long long sum;scanf ("%s", str);for (int i = 0; i < strlen (str); i++) {if (str[i] == '+' || str[i] == '*')op[t++] = str[i];else {sum = 0;while (str[i] >= '0' && str[i] <= '9') {sum = sum * 10 + str[i] - '0';i++;}num[t] = sum;i--;}}return t + 1;}int main () {int t;int count;scanf ("%d", &t);while (t--) {count = init();printf ("The maximum and minimum are %lld and %lld.\n", caculate_max(count), caculate_min(count));}return 0;}