71 lines
1.9 KiB
C++
71 lines
1.9 KiB
C++
/* HDU1427 速算24点 */
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#include <iostream>
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#include <algorithm>
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#include <stdio.h>
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#include <string.h>
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using namespace std;
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const int N = 4;
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int a[N];
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bool flag;
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bool dfs(int cnt, int result1, int result2) {
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if (cnt == N - 1) {
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if (result1 + result2 == 24 || result1 - result2 == 24 || result1 * result2 == 24)
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flag = true;
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if (result2 != 0 && result1 % result2 == 0 && result1 / result2 == 24)
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flag = true;
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} else if (!flag) {
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// 先算前2项
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dfs(cnt + 1, result1 + result2, a[cnt + 1]);
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dfs(cnt + 1, result1 - result2, a[cnt + 1]);
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dfs(cnt + 1, result1 * result2, a[cnt + 1]);
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if (result2 != 0 && result1 % result2 == 0)
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dfs(cnt + 1, result1 / result2, a[cnt + 1]);
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// 先算后2项，相当与后2项计算是加括号的
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dfs(cnt + 1, result1, result2 + a[cnt + 1]);
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dfs(cnt + 1, result1, result2 - a[cnt + 1]);
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dfs(cnt + 1, result1, result2 * a[cnt + 1]);
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if (a[cnt + 1] != 0 && result2 % a[cnt + 1] == 0)
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dfs(cnt + 1, result1, result2 / a[cnt + 1]);
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}
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return false;
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}
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int main() {
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for (;;) {
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char s[4];
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for (int i = 0; i < N; i++) {
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if (scanf("%s", s) == EOF)
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return 0;
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if (strlen(s) == 2)
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a[i] = 10;
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else if (s[0] == 'A')
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a[i] = 1;
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else if (s[0] == 'J')
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a[i] = 11;
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else if (s[0] == 'Q')
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a[i] = 12;
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else if (s[0] == 'K')
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a[i] = 13;
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else
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a[i] = s[0] - '0';
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}
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sort(a, a + N);
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flag = false;
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do {
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dfs(1, a[0], a[1]);
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if (flag)
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break;
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} while (next_permutation(a, a + N));
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printf("%s\n", flag ? "Yes" : "No");
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}
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return 0;
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}
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