679

Author: LuYanFCP

README.md

@@ -127,6 +127,10 @@ Leetcode刷题记录
 + No.51 [cpp](剑指offer/cpp/51.cpp) [python](剑指offer/python/51.py)
 + No.59 [cpp](剑指offer/cpp/59.cpp)
 
+### 暴力破解
+
++ No. 679 [cpp](cpp/679.cpp)
+
 ## 专题
 
 ### 状态DP

cpp/679.cpp

@@ -0,0 +1,76 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+
+class Solution {
+public:
+    static constexpr int TARGET = 24;
+    static constexpr double EPSILON = 1e-6;
+    enum {ADD = 0, MULTIPLY = 1, SUBTRACT = 2, DIVIDE = 3};
+
+    bool judgePoint24(vector<int> &nums) {
+        vector<double> l;
+        for (const int &num : nums) {
+            l.emplace_back(static_cast<double>(num));
+        }
+        return solve(l);
+    }
+
+    bool solve(vector<double> &l) {
+        if (l.size() == 0) {
+            return false;
+        }
+        if (l.size() == 1) {
+            return fabs(l[0] - TARGET) < EPSILON;
+        }
+        int size = l.size();
+        for (int i = 0; i < size; i++) {
+            for (int j = 0; j < size; j++) {
+                if (i != j) {
+                    vector<double> list2 = vector<double>();
+                    for (int k = 0; k < size; k++) {
+                        if (k != i && k != j) {
+                            list2.emplace_back(l[k]);
+                        }
+                    }
+                    for (int k = 0; k < 4; k++) {
+                        if (k < 2 && i > j) {
+                            continue;
+                        }
+                        switch (k)
+                        {
+                        case ADD:
+                            list2.emplace_back(l[i] + l[j]);
+                            break;
+                        case MULTIPLY:
+                            list2.emplace_back(l[i] * l[j]);
+                            break;
+                        case SUBTRACT:
+                            list2.emplace_back(l[i] - l[j]);
+                            break;
+                        case DIVIDE: 
+                            if (fabs(l[j]) < EPSILON) {
+                                continue;
+                            }
+                            list2.emplace_back(l[i] / l[j]);
+                            break;
+                        }
+
+                        if (solve(list2)) {
+                            return true;
+                        }
+                        list2.pop_back();  // 全排列
+                    }
+                }
+            }
+        }
+        return false;
+    }
+};
+
+
+int main(int argc, char const *argv[])
+{
+    
+    return 0;
+}