feat: add solutions to lcof2 problems: No.014,015

lcof2/剑指 Offer II 014. 字符串中的变位词/Solution.cpp

@@ -1,46 +1,45 @@
-class Solution {
-public:
-    bool checkInclusion(string s1, string s2) {
-
-        int len1 = s1.size();
-        int len2 = s2.size();
-
-        if (len2 < len1) {
-            return false;
-        }
-
-        int count[30] = {0};
-
-        for (int i = 0; i < len1; ++i) {
-            ++count[s1[i] - 'a'];
-            --count[s2[i] - 'a'];
-        }
-
-        int l = 0;
-        int r = len1 - 1;
-
-        while (r < len2) {
-
-            bool flag = true;
-
-            for (int i : count) {
-                if (i != 0) {
-                    flag = false;
-                }
-            }
-
-            if (flag) {
-                return true;
-            }
-
-            if (r + 1 >= len2) {
-                break;
-            }
-
-            ++count[s2[l++] - 'a'];
-            --count[s2[++r] - 'a'];
-        }
-
-        return false;
-    }
+class Solution {
+public:
+    bool checkInclusion(string s1, string s2) {
+        int m = s1.size(), n = s2.size();
+        if (m > n) {
+            return false;
+        }
+        vector<int> cnt(26);
+        for (int i = 0; i < m; ++i) {
+            --cnt[s1[i] - 'a'];
+            ++cnt[s2[i] - 'a'];
+        }
+        int diff = 0;
+        for (int x : cnt) {
+            if (x != 0) {
+                ++diff;
+            }
+        }
+        if (diff == 0) {
+            return true;
+        }
+        for (int i = m; i < n; ++i) {
+            int a = s2[i - m] - 'a';
+            int b = s2[i] - 'a';
+            if (cnt[a] == 0) {
+                ++diff;
+            }
+            --cnt[a];
+            if (cnt[a] == 0) {
+                --diff;
+            }
+            if (cnt[b] == 0) {
+                ++diff;
+            }
+            ++cnt[b];
+            if (cnt[b] == 0) {
+                --diff;
+            }
+            if (diff == 0) {
+                return true;
+            }
+        }
+        return false;
+    }
 };

lcof2/剑指 Offer II 014. 字符串中的变位词/Solution.go

@@ -1,31 +1,41 @@
 func checkInclusion(s1 string, s2 string) bool {
-	n1, n2 := len(s1), len(s2)
-	if n1 > n2 {
+	m, n := len(s1), len(s2)
+	if m > n {
 		return false
 	}
-	window := make([]int, 26)
-	for i := 0; i < n1; i++ {
-		window[s1[i]-'a']++
-		window[s2[i]-'a']--
+	cnt := [26]int{}
+	for i := 0; i < m; i++ {
+		cnt[s1[i]-'a']--
+		cnt[s2[i]-'a']++
 	}
-	if check(window) {
+	diff := 0
+	for _, x := range cnt {
+		if x != 0 {
+			diff++
+		}
+	}
+	if diff == 0 {
 		return true
 	}
-	for i := n1; i < n2; i++ {
-		window[s2[i]-'a']--
-		window[s2[i-n1]-'a']++
-		if check(window) {
+	for i := m; i < n; i++ {
+		a, b := s2[i-m]-'a', s2[i]-'a'
+		if cnt[a] == 0 {
+			diff++
+		}
+		cnt[a]--
+		if cnt[a] == 0 {
+			diff--
+		}
+		if cnt[b] == 0 {
+			diff++
+		}
+		cnt[b]++
+		if cnt[b] == 0 {
+			diff--
+		}
+		if diff == 0 {
 			return true
 		}
 	}
 	return false
-}
-
-func check(window []int) bool {
-	for _, cnt := range window {
-		if cnt != 0 {
-			return false
-		}
-	}
-	return true
 }

lcof2/剑指 Offer II 014. 字符串中的变位词/Solution.java

@@ -1,28 +1,45 @@
-class Solution {
-    public boolean checkInclusion(String s1, String s2) {
-        int n1 = s1.length(), n2 = s2.length();
-        if (n1 > n2) {
-            return false;
-        }
-        int[] window = new int[26];
-        for (int i = 0; i < n1; i++) {
-            window[s1.charAt(i) - 'a']++;
-            window[s2.charAt(i) - 'a']--;
-        }
-        if (check(window)) {
-            return true;
-        }
-        for (int i = n1; i < n2; i++) {
-            window[s2.charAt(i) - 'a']--;
-            window[s2.charAt(i - n1) - 'a']++;
-            if (check(window)) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    private boolean check(int[] window) {
-        return Arrays.stream(window).allMatch(cnt -> cnt == 0);
-    }
-}
+class Solution {
+    public boolean checkInclusion(String s1, String s2) {
+        int m = s1.length();
+        int n = s2.length();
+        if (m > n) {
+            return false;
+        }
+        int[] cnt = new int[26];
+        for (int i = 0; i < m; ++i) {
+            --cnt[s1.charAt(i) - 'a'];
+            ++cnt[s2.charAt(i) - 'a'];
+        }
+        int diff = 0;
+        for (int x : cnt) {
+            if (x != 0) {
+                ++diff;
+            }
+        }
+        if (diff == 0) {
+            return true;
+        }
+        for (int i = m; i < n; ++i) {
+            int a = s2.charAt(i - m) - 'a';
+            int b = s2.charAt(i) - 'a';
+            if (cnt[a] == 0) {
+                ++diff;
+            }
+            --cnt[a];
+            if (cnt[a] == 0) {
+                --diff;
+            }
+            if (cnt[b] == 0) {
+                ++diff;
+            }
+            ++cnt[b];
+            if (cnt[b] == 0) {
+                --diff;
+            }
+            if (diff == 0) {
+                return true;
+            }
+        }
+        return false;
+    }
+}

lcof2/剑指 Offer II 014. 字符串中的变位词/Solution.py

@@ -1,20 +1,27 @@
-class Solution:
-    def checkInclusion(self, s1: str, s2: str) -> bool:
-        n1, n2 = len(s1), len(s2)
-        if n1 > n2:
-            return False
-        window = [0 for _ in range(26)]
-        for i in range(n1):
-            window[ord(s1[i]) - ord('a')] += 1
-            window[ord(s2[i]) - ord('a')] -= 1
-        if self.check(window):
-            return True
-        for i in range(n1, n2):
-            window[ord(s2[i]) - ord('a')] -= 1
-            window[ord(s2[i - n1]) - ord('a')] += 1
-            if self.check(window):
-                return True
-        return False
-
-    def check(self, window: List[int]) -> bool:
-        return all([cnt == 0 for cnt in window])
+class Solution:
+    def checkInclusion(self, s1: str, s2: str) -> bool:
+        m, n = len(s1), len(s2)
+        if m > n:
+            return False
+        cnt = Counter()
+        for a, b in zip(s1, s2):
+            cnt[a] -= 1
+            cnt[b] += 1
+        diff = sum(x != 0 for x in cnt.values())
+        if diff == 0:
+            return True
+        for i in range(m, n):
+            a, b = s2[i - m], s2[i]
+            if cnt[a] == 0:
+                diff += 1
+            cnt[a] -= 1
+            if cnt[a] == 0:
+                diff -= 1
+            if cnt[b] == 0:
+                diff += 1
+            cnt[b] += 1
+            if cnt[b] == 0:
+                diff -= 1
+            if diff == 0:
+                return True
+        return False

lcof2/剑指 Offer II 014. 字符串中的变位词/Solution.ts

@@ -0,0 +1,41 @@
+function checkInclusion(s1: string, s2: string): boolean {
+    const m = s1.length;
+    const n = s2.length;
+    if (m > n) {
+        return false;
+    }
+    const cnt: number[] = new Array(26).fill(0);
+    for (let i = 0; i < m; ++i) {
+        --cnt[s1[i].charCodeAt(0) - 'a'.charCodeAt(0)];
+        ++cnt[s2[i].charCodeAt(0) - 'a'.charCodeAt(0)];
+    }
+    let diff = 0;
+    for (const x of cnt) {
+        if (x !== 0) {
+            ++diff;
+        }
+    }
+    if (diff === 0) {
+        return true;
+    }
+    for (let i = m; i < n; ++i) {
+        const a = s2[i - m].charCodeAt(0) - 'a'.charCodeAt(0);
+        const b = s2[i].charCodeAt(0) - 'a'.charCodeAt(0);
+        if (cnt[a] === 0) {
+            ++diff;
+        }
+        if (--cnt[a] === 0) {
+            --diff;
+        }
+        if (cnt[b] === 0) {
+            ++diff;
+        }
+        if (++cnt[b] === 0) {
+            --diff;
+        }
+        if (diff === 0) {
+            return true;
+        }
+    }
+    return false;
+}