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面试题 08.14:布尔运算

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huangge1199 2021-06-03 13:32:57 +08:00
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src/main/java/leetcode/editor/cn/BooleanEvaluationLcci.java Normal file
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//给定一个布尔表达式和一个期望的布尔结果 result，布尔表达式由 0 (false)、1 (true)、& (AND)、 | (OR) 和 ^ (XOR)
// 符号组成。实现一个函数，算出有几种可使该表达式得出 result 值的括号方法。
//
// 示例 1:
//
// 输入: s = "1^0|0|1", result = 0
//
//输出: 2
//解释: 两种可能的括号方法是
//1^(0|(0|1))
//1^((0|0)|1)
//
//
// 示例 2:
//
// 输入: s = "0&0&0&1^1|0", result = 1
//
//输出: 10
//
// 提示：
//
//
// 运算符的数量不超过 19 个
//
// Related Topics 栈 字符串
// 👍 43 👎 0
package leetcode.editor.cn;
//面试题 08.14:布尔运算
public class BooleanEvaluationLcci{
public static void main(String[] args) {
//测试代码
Solution solution = new BooleanEvaluationLcci().new Solution();
}
//力扣代码
//leetcode submit region begin(Prohibit modification and deletion)
class Solution {
public int countEval(String s, int result) {
if (s.length() == 0) {
return 0;
}
if (s.length() == 1) {
return (s.charAt(0) - '0') == result ? 1 : 0;
}
char[] ch = s.toCharArray();
int[][][] dp = new int[ch.length][ch.length][2];
for (int i = 0; i < ch.length; i++) {
if (ch[i] == '0' || ch[i] == '1') {
dp[i][i][ch[i] - '0'] = 1;
}
}
for (int len = 2; len <= ch.length; len += 2) {
for (int start = 0; start <= ch.length - len; start += 2) {
int end = start + len;
for (int k = start + 1; k <= end - 1; k += 2) {
if (ch[k] == '&') {
dp[start][end][0] += dp[start][k - 1][0] * dp[k + 1][end][0] + dp[start][k - 1][0] * dp[k + 1][end][1] + dp[start][k - 1][1] * dp[k + 1][end][0];
dp[start][end][1] += dp[start][k - 1][1] * dp[k + 1][end][1];
}
if (ch[k] == '|') {
dp[start][end][0] += dp[start][k - 1][0] * dp[k + 1][end][0];
dp[start][end][1] += dp[start][k - 1][0] * dp[k + 1][end][1] + dp[start][k - 1][1] * dp[k + 1][end][0] + dp[start][k - 1][1] * dp[k + 1][end][1];
}
if (ch[k] == '^') {
dp[start][end][0] += dp[start][k - 1][0] * dp[k + 1][end][0] + dp[start][k - 1][1] * dp[k + 1][end][1];
dp[start][end][1] += dp[start][k - 1][1] * dp[k + 1][end][0] + dp[start][k - 1][0] * dp[k + 1][end][1];
}
}
}
}
return dp[0][ch.length - 1][result];
}
}
//leetcode submit region end(Prohibit modification and deletion)
}

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src/main/java/leetcode/editor/cn/BooleanEvaluationLcci.md Normal file
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<p>给定一个布尔表达式和一个期望的布尔结果 result，布尔表达式由 <code>0</code> (false)、<code>1</code> (true)、<code>&amp;</code> (AND)、 <code>|</code> (OR) 和 <code>^</code> (XOR) 符号组成。实现一个函数，算出有几种可使该表达式得出 result 值的括号方法。</p>
<p><strong>示例 1:</strong></p>
<pre><strong>输入: </strong>s = &quot;1^0|0|1&quot;, result = 0
<strong>输出: </strong>2
<strong>解释:</strong>&nbsp;两种可能的括号方法是
1^(0|(0|1))
1^((0|0)|1)
</pre>
<p><strong>示例 2:</strong></p>
<pre><strong>输入: </strong>s = &quot;0&amp;0&amp;0&amp;1^1|0&quot;, result = 1
<strong>输出: </strong>10</pre>
<p><strong>提示：</strong></p>
<ul>
<li>运算符的数量不超过 19 个</li>
</ul>
<div><div>Related Topics</div><div><li>栈</li><li>字符串</li></div></div>\n<div><li>👍 43</li><li>👎 0</li></div>