optimize 567

Author: Danieldu

150/567.permutation-in-string.cpp

@@ -0,0 +1,60 @@
+/*
+ * @lc app=leetcode id=567 lang=cpp
+ *
+ * [567] Permutation in String
+ */
+
+// @lc code=start
+#include "bits/stdc++.h"
+using namespace std;
+
+class Solution {
+    public:
+        bool checkInclusion(string s1, string s2) {
+            int n1 = s1.size(), n2 = s2.size();
+            if (n1 > n2) return false;  
+            vector<int> countS1(26, 0), countWin(26, 0);
+            
+            for (char c: s1) {
+                countS1[c - 'a']++;
+            }
+            
+            for (int i = 0; i < n1; i++) {
+                countWin[s2[i] - 'a']++;
+            }
+    
+            int matchCount = 0;
+            for (int i = 0; i < 26; i++) {
+                if (countS1[i] == countWin[i]) {
+                    matchCount++;
+                }
+            }
+            
+            if (matchCount == 26) return true;
+            
+            for (int i = n1; i < n2; i++) {
+                int newChar = s2[i] - 'a';
+                int oldChar = s2[i - n1] - 'a';
+                
+                if (countS1[oldChar] == countWin[oldChar]) {
+                    matchCount--;
+                }
+                countWin[oldChar]--;
+                if (countS1[oldChar] == countWin[oldChar]) {
+                    matchCount++;
+                }
+                
+                if (countS1[newChar] == countWin[newChar]) {
+                    matchCount--;
+                }
+                countWin[newChar]++;
+                if (countS1[newChar] == countWin[newChar]) {
+                    matchCount++;
+                } 
+                if (matchCount == 26) return true;
+            }
+            return false;
+        }
+    };
+// @lc code=end
+