hdu 1427 速算24点

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原题链接：http://acm.hdu.edu.cn/showproblem.php?pid=1427
参照<<编程之美>>上的写法，时间卡的挺紧的，用cin tle scanf过了/(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 LOCAL    freopen("in.txt", "r", stdin);    freopen("out.txt", "w+", stdout);#endif    init();    while (~scanf("%s %s %s %s", ret[0], ret[1], ret[2], ret[3])) {        puts(solve() ? "Yes" : "No");    }    return 0;}

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