CCPC杭州站 HDU5938 Four Operations 贪心 枚举

http://acm.hdu.edu.cn/showproblem.php?pid=5938

给一个长度最长20且大于5的数字（1~9）字符串，要求按+-*/顺序插入数字之间，使得结果最大

比赛的时候一直认为除号放最后一定是最优的，没有找出范例...其实有这种数据

111991
1+11-9*9/1=-69
11+1-9*9/1=-69
1+1-1*9/91=2
1+1-1*9/91=2

所以要枚举一下除号位置，哎好气哟

#include <string>#include <cstring>#include <iostream>using namespace std;typedef long long LL;string s;LL Count(int l, int r) {    LL ret = 0;    for (int i = l; i < r; i ++) ret = ret * 10 + s[i] - '0';    return ret;}LL solve(int p1, int p2, int p3, int p4) {    LL a1, a2, a3, a4, a5;    a1 = Count(0, p1);    a2 = Count(p1, p2);    a3 = Count(p2, p3);    a4 = Count(p3, p4);    a5 = Count(p4, s.size());    //cout << a1 << "+" << a2 << "-"<< a3 << "*"<< a4 << "/"<< a5 << "=" << a1 + a2 - a3 * a4 / a5 << '\n';    return a1 + a2 - a3 * a4 / a5;}int main() {    std::ios::sync_with_stdio(false);    int T, kase = 0; cin >> T;    while (T--) {        cin >> s;        LL res = -0x3f3f3f3f;        for (int i = s.size() - 1; i > 3; i --) {            int p4 = i, p3 = i-1, p2 = i-2, p1 = 1;            res = max(res, solve(p1, p2, p3, p4));            p1 = p2 - 1;            res = max(res, solve(p1, p2, p3, p4));        }        cout << "Case #" << ++kase << ": " << res << '\n';    }    return 0;}//111991