'commit'

TangDou/CSP-J/J2_2020/ZhuanTi_BiaoDaShi/ToPostFix/InFixToPostFix_LuoJi.cpp

@@ -0,0 +1,43 @@
+#include <bits/stdc++.h>
+using namespace std;
+/*
+中缀逻辑表达式转后缀逻辑表达式
+
+测试用例：
+0&(0|1|0)
+
+答案：
+001|0|&
+*/
+unordered_map<char, int> g{{'|', 1}, {'&', 2}};
+string s, t;
+stack<char> stk;
+
+int main() {
+    cin >> s;
+    for (int i = 0; i < s.size(); i++) {
+        if (isdigit(s[i]) || isalpha(s[i]))
+            t += s[i];
+        else if (s[i] == '(')
+            stk.push(s[i]);
+        else if (s[i] == ')') {
+            while (stk.top() != '(') {
+                t += stk.top();
+                stk.pop();
+            }
+            stk.pop();
+        } else {
+            while (stk.size() && g[s[i]] <= g[stk.top()]) {
+                t += stk.top();
+                stk.pop();
+            }
+            stk.push(s[i]);
+        }
+    }
+    while (stk.size()) {
+        t += stk.top();
+        stk.pop();
+    }
+    cout << t << endl;
+    return 0;
+}

TangDou/CSP-J/J2_2020/ZhuanTi_BiaoDaShi/ToPostFix/InFixToPostfix.cpp

@@ -0,0 +1,77 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+// 中缀表达式转后缀表达式
+/*
+测试用例1:
+a+b*c+(d*e+f)*g
+
+答案：
+abc*+de*f+g*+
+
+
+测试用例2：
+(6+3*(7-4))-8/2
+
+答案：
+6 3 7 4 - * + 8 2 / -
+
+测试用例3：
+(24*(9+6/3-5)+4)
+答案：
+24 9 6 3 / + 5 - * 4 +
+
+测试用例4:
+2*3*2+5/3
+
+*/
+
+unordered_map<char, int> g{{'+', 1}, {'-', 1}, {'*', 2}, {'/', 2}}; // 操作符优化级
+string t;                                                           // 结果串
+stack<char> stk;                                                    // 栈
+// 中缀转后缀
+string infixToPostfix(string s) {
+    for (int i = 0; i < s.size(); i++) {
+        // ①数字
+        if (isdigit(s[i])) {
+            int x = 0;
+            while (i < s.size() && isdigit(s[i])) {
+                x = x * 10 + s[i] - '0';
+                i++;
+            }
+            i--;
+            t += to_string(x), t += ' ';
+        } else if (isalpha(s[i])) // ②字符,比如a,b,c
+            t += s[i], t += ' ';
+        else if (s[i] == '(')          // ③左括号
+            stk.push(s[i]);            // 左括号入栈
+        else if (s[i] == ')') {        // ④右括号
+            while (stk.top() != '(') { // 让栈中元素(也就是+-*/和左括号)一直出栈，直到匹配的左括号出栈
+                t += stk.top(), t += ' ';
+                stk.pop();
+            }
+            stk.pop(); // 左括号也需要出栈
+        } else {
+            // ⑤操作符 +-*/
+            while (stk.size() && g[s[i]] <= g[stk.top()]) {
+                t += stk.top(), t += ' ';
+                stk.pop();
+            }
+            stk.push(s[i]); // 将自己入栈
+        }
+    }
+    // 当栈不为空时，全部输出
+    while (stk.size()) {
+        t += stk.top(), t += ' ';
+        stk.pop();
+    }
+    return t;
+}
+
+int main() {
+    string infix = "(24*(9+6/3-5)+4)";
+    string postfix = infixToPostfix(infix);
+    cout << "中缀表达式: " << infix << endl;
+    cout << "后缀表达式: " << postfix << endl;
+    return 0;
+}

TangDou/CSP-J/J2_2020/ZhuanTi_BiaoDaShi/ToPostFix/PrefixToPostfix_WithBlank.cpp

@@ -0,0 +1,45 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+/*
+测试样例：
++ 23 34
+
+/ + 4 2 * 3 5
+*/
+
+// 将前缀表达式转换为后缀表达式(带空格版本)
+
+// 判断字符是否是操作符
+bool isOp(string c) {
+    return c == "+" || c == "-" || c == "*" || c == "/";
+}
+
+string prefixToPostfix(string s) {
+    stack<string> stk;
+    string c; // 子串
+    vector<string> q;
+    stringstream s1(s);             // 构造字符串流，处理带空格的后缀表达式
+    while (s1 >> c) q.push_back(c); // 将每个子串抽取出来
+
+    for (int i = q.size() - 1; i >= 0; i--) {
+        string c = q[i];
+        if (isOp(c)) {
+            string a = stk.top();
+            stk.pop();
+            string b = stk.top();
+            stk.pop();
+            stk.push(a + " " + b + " " + c);
+        } else
+            stk.push(c); // 如果是操作数，将其转换为整数并入栈
+    }
+    return stk.top();
+}
+
+int main() {
+    string prefix = "/ + 4 2 * 3 5"; // / + 4 2 * 3 5 --> vector<>={/ + 4 2 * 3 5}
+    string postfix = prefixToPostfix(prefix);
+    cout << "前缀表达式: " << prefix << endl;
+    cout << "后缀表达式: " << postfix << endl;
+    return 0;
+}

TangDou/CSP-J/J2_2020/ZhuanTi_BiaoDaShi/ToPostFix/PrefixToPostfix_WithoutBlank.cpp

@@ -0,0 +1,37 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+// 判断字符是否是操作符
+bool isOp(string c) {
+    return c == "+" || c == "-" || c == "*" || c == "/";
+}
+
+string prefixToPostfix(string s) {
+    stack<string> stk;
+    for (int i = s.size() - 1; i >= 0; i--) {
+        string c = string(1, s[i]);
+        if (isOp(c)) { // 操作符
+            string a = stk.top();
+            stk.pop();
+            string b = stk.top();
+            stk.pop();
+            stk.push(a + b + c);
+        } else
+            stk.push(c); // 字母a~z
+    }
+    return stk.top();
+}
+
+int main() {
+    // * + 12 23 * 3 + 45 6
+    string prefix = "*+ab*c+de";
+    string postfix = prefixToPostfix(prefix);
+    cout << "前缀表达式: " << prefix << endl;
+    cout << "后缀表达式: " << postfix << endl;
+    return 0;
+}
+/*
+Prefix Expression: *+ab*c+de
+Postfix Expression: ab+cde+**
+Infix Expression: ((a+b)*(c*(d+e)))
+*/

TangDou/CSP-J/J2_2020/ZhuanTi_BiaoDaShi/ToPostFix/TD.cpp

@@ -0,0 +1,30 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+bool isOp(string  c){
+    return c == "+" || c == "-" || c == "*" || c == "/";
+}
+int eval(string s){
+    stack<int> stk;
+    stringstream s1(s);
+    string c;
+    while (s1>>c){
+        if(isOp(c)){
+            int a = stk.top();
+            stk.pop();
+            int b = stk.top();
+            stk.pop();
+            if (c == "+") stk.push(b + a);
+            if (c == "-") stk.push(b - a);
+            if (c == "*") stk.push(b * a);
+            if (c == "/") stk.push(b / a);
+        }else
+            stk.push(stoi(c));
+    }
+    return stk.top();
+}
+int main() {
+    string s = "24 9 6 3 / + 5 - * 4 +";
+    cout << "answer:" << eval(s) << endl;
+    return 0;
+}