hdu 1427 速算24點

題目連接

http://acm.hdu.edu.cn/showproblem.php?pid=1427?

速算24點

Description

速算24點相信絕大多數人都玩過。就是隨機給你四張牌，包括A(1),2,3,4,5,6,7,8,9,10,J(11),Q(12),K(13)。要求只用'+','-','*','/'運算符以及括號改變運算順序，使得最終運算結果為24(每個數必須且僅能用一次)。游戲很簡單，但遇到無解的情況往往讓人很郁悶。你的任務就是針對每一組隨機產生的四張牌，判斷是否有解。我們另外規定，整個計算過程中都不能出現小數。

Input

每組輸入數據占一行，給定四張牌。

Output

每一組輸入數據對應一行輸出。如果有解則輸出"Yes"，無解則輸出"No"。

Sample Input

A 2 3 6
3 3 8 8

Sample Output

Yes
No

參照<<編程之美>>上的寫法，時間卡的挺緊的，用cin tle scanf過了/(ㄒoㄒ)/~~

#include<algorithm>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<vector>
#include<string>
#include<map>
using std::map;
using std::fabs;
using std::pair;
using std::swap;
using std::string;
using std::next_permutation;
#define pb(e) push_back(e)
#define sz(c) (int)(c).size()
#define mp(a, b) make_pair(a, b)
#define all(c) (c).begin(), (c).end()
#define iter(c) decltype((c).begin())
#define cls(arr, val) memset(arr, val, sizeof(arr))
#define cpresent(c, e) (find(all(c), (e)) != (c).end())
#define rep(i, n) for(int i = 0; i < (int)n; i++)
#define tr(c, i) for(iter(c) i = (c).begin(); i != (c).end(); ++i)
const int N = 20;
const double eps = 1E-7;
const int INF = 0x3f3f3f3f;
typedef unsigned long long ull;
int arr[4];
char ret[4][10];
map<string, int> A;
bool dfs(int n) {if (1 == n) {return arr[0] == 24;}for (int i = 0; i < n; i++) {for (int j = i + 1; j < n; j++) {int a = arr[i], b = arr[j];arr[j] = arr[n - 1];arr[i] = a + b;if (dfs(n - 1)) return true;arr[i] = a - b;if (dfs(n - 1)) return true;arr[i] = b - a;if (dfs(n - 1)) return true;arr[i] = a * b;if (dfs(n - 1)) return true;if (b != 0 && 0 == a % b) {arr[i] = a / b;if (dfs(n - 1)) return true;}if (a != 0 && 0 == b % a) {arr[i] = b / a;if (dfs(n - 1)) return true;}arr[i] = a;arr[j] = b;}}return false;
}
void init() {A["A"] = 1;A["2"] = 2;A["3"] = 3;A["4"] = 4;A["5"] = 5;A["6"] = 6;A["7"] = 7;A["8"] = 8;A["9"] = 9;A["10"] = 10;A["J"] = 11;A["Q"] = 12;A["K"] = 13;
}
bool solve() {for (int i = 0; i < 4; i++) {arr[i] = A[ret[i]];}do {if (dfs(4)) return true;} while (next_permutation(arr, arr + 4));return false;
}
int main() {
#ifdef LOCALfreopen("in.txt", "r", stdin);freopen("out.txt", "w+", stdout);
#endifinit();while (~scanf("%s %s %s %s", ret[0], ret[1], ret[2], ret[3])) {puts(solve() ? "Yes" : "No");}return 0;
}