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Author: whd

420 Strong Password Checker .cpp

@@ -0,0 +1,101 @@
+class Solution {
+public:
+    int strongPasswordChecker(string s) {
+        const int inf = 0x3f3f3f3f;
+        auto n = s.size();
+        const int charset = 2 + 2 + 2;
+        vector<vector<vector<vector<vector<int>>>>> f(s.size() + 1, vector<vector<vector<vector<int>>>>(21, vector<vector
+            <vector<int>>>(charset, vector<vector<int>>(3, vector<int>(8, inf)))));
+        // int f[100][21][charset][3][1 << 3];
+        // memset(f, inf, sizeof(f));
+        f[0][0][0][0][0] = 0;
+        for (auto &ch : s) {
+            if (isdigit(ch)) {
+                ch -= '0';
+            } else if (isupper(ch)) {
+                ch -= 'A';
+                ch += 10;
+            } else {
+                ch -= 'a';
+                ch += 36;
+            }
+        }
+        char last = s[0];
+        for (int i = 0; i < s.size(); i++) {
+            bool dif = (i && s[i] != last);
+            int lastv = i ? s[i - 1] : 0;
+            last = s[i];
+            if (s[i] < 10) {
+                s[i] = 0 ^ (dif ^ (lastv & 1));
+            } else if (s[i] < 36) {
+                s[i] = 2 ^ (dif ^ (lastv & 1));
+            } else {
+                s[i] = 4 ^ (dif ^ (lastv & 1));
+            }
+            // cout << int(s[i]) << endl;
+        }
+        auto type = [] (char x) {
+            if (x < 2) {
+                return 1 << 0;
+            } else if (x < 4) {
+                return 1 << 1;
+            } else {
+                return 1 << 2;
+            }
+        };
+        for (int len = 0; len < 20; len++) {
+            for (int i = 0; i <= n; i++) {
+                for (int lastchar = 0; lastchar < charset; lastchar++) {
+                    for (int repeat = 0; repeat < 3; repeat++) {
+                        for (int state = 0; state < 8; state++) {
+                            if (f[i][len][lastchar][repeat][state] >= inf) {
+                                continue;
+                            }
+                            int x = f[i][len][lastchar][repeat][state];
+                            // keep
+                            if (i < n) {
+                                {
+                                    char ch = s[i];
+                                    if (repeat < 2 || lastchar != ch) {
+                                        int &y = f[i + 1][len + 1][ch][lastchar == ch ? repeat + 1 : 1][state | type(ch)];
+                                        y = min(x, y);
+                                    }
+                                }
+                                // remove
+                                {
+                                    int &y = f[i + 1][len][lastchar][repeat][state];
+                                    y = min(y, x + 1);
+                                }
+                            }
+                            // add or change
+                            {
+                                for (int ch = 0; ch < charset; ch++) {
+                                    if (repeat < 2 || lastchar != ch) {
+                                        {
+                                            int &y = f[i][len + 1][ch][lastchar == ch ? repeat + 1 : 1][state | type(ch)];
+                                            y = min(y, x + 1);
+                                        }
+                                        if (i < n) {
+                                            int &y = f[i + 1][len + 1][ch][lastchar == ch ? repeat + 1 : 1][state | type(ch)]
+                                                ;
+                                            y = min(y, x + 1);
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        int ans = inf;
+        for (int len = 6; len <= 20; len++) {
+            for (int ch = 0; ch < charset; ch++) {
+                for (int repeat = 0; repeat < 3; repeat++) {
+                    ans = min(ans, f[s.size()][len][ch][repeat][7]);
+                }
+            }
+        }
+        return ans;
+    }
+};