Nếu bạn kiểm tra số lần xuất hiện của 'o' trong chuỗi 'school', kết quả là 2 Show
ví dụ 1. Kiểm tra sự xuất hiện của một ký tự bằng vòng lặp
đầu ra Enter a string: school Enter a letter to check: o 2 Trong ví dụ trên, người dùng được nhắc nhập một chuỗi và ký tự để kiểm tra
ví dụ 2. Kiểm tra sự xuất hiện của một ký tự bằng Regex
đầu ra Enter a string: school Enter a letter to check: o 2 Trong ví dụ trên, một biểu thức chính quy (regex) được sử dụng để tìm sự xuất hiện của một chuỗi
Để hoàn thành nhiệm vụ này, chúng tôi sẽ duy trì một mảng gọi là freq với cùng kích thước với độ dài của chuỗi. Freq sẽ được sử dụng để duy trì số lượng của từng ký tự có trong chuỗi. Bây giờ, lặp qua chuỗi để so sánh từng ký tự với phần còn lại của chuỗi. Tăng số phần tử tương ứng trong freq. Cuối cùng, lặp qua freq để hiển thị tần số của các ký tự Bạn đang kiểm tra điều gì trong điều kiện if? Trong bài viết này, chúng ta được cung cấp một chuỗi, nhiệm vụ của chúng ta là tìm sự xuất hiện của một ký tự trong chuỗi với sự trợ giúp của một hàm do người dùng định nghĩa. Example: Input : "hello" Output : h occur 1 times e occur 1 times l occur 2 times o occur 1 times Explanation : here "hello" have 1 h, so it have 1 value. as same e have 1, l have 2 , o have 1. Example 2: Input : "did" Output: d occur 2 times i occur 1 times Cách tiếp cận 1. Theo cách tiếp cận này, chúng tôi sử dụng cấu trúc dữ liệu bản đồ để lưu trữ số lần các ký tự xuất hiện
Thí dụ. Ví dụ này cho thấy việc sử dụng phương pháp được giải thích ở trên Javascript
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times1 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2_______5_______3 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times4 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2_______5_______1 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times8 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times0 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times1 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3
g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3
g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times9
h occur 1 times e occur 1 times l occur 2 times o occur 1 times2
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times1 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2_______5_______3 h occur 1 times e occur 1 times l occur 2 times o occur 1 times7 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2_______5_______1
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 <script> 2h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 <script> 4
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2 0h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2______138_______2
g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times1 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2______139_______4 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2_______139_______6 //function to print occurrence of character 7h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2_______5_______1 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 1 2 3h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 5 6h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2 function 0h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2_______5_______1 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 function 4h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 function 6function 7 function 8h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times3 printans( ans ) 1h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times1 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times1____142_______5 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7_______5_______00 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3
g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times09
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times11_______5_______12 6
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times15 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times16 đầu ra h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times Cách tiếp cận 2. Trong cách tiếp cận này, chúng tôi sử dụng vòng lặp for lồng nhau để lặp qua chuỗi và đếm cho từng ký tự trong chuỗi.
Thí dụ. Ví dụ này cho thấy việc sử dụng phương pháp được giải thích ở trên Javascript
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times19
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times22
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times1 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2_______5_______26 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2_______139_______6 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times29 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2_______5_______1 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 1_______5_______34h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times35 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 5 6h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2_______5_______42 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2_______5_______3 h occur 1 times e occur 1 times l occur 2 times o occur 1 times7 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2_______5_______1 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times49 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times51 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times3 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times54 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times1 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times1 //function to print occurrence of character 6h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times59 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times1 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times1 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times62_______5_______63 6g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times1 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times1 //function to print occurrence of character 6h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times69 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times1 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times1
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times73 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times1 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 //function to print occurrence of character 6h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times80 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7_______5_______82 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times7 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times2 g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3
g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times3
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times09
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times93_______5_______94 6
h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times97 h occurs 1 times e occurs 1 times l occurs 3 times o occurs 2 times w occurs 1 times r occurs 1 times d occurs 1 times16 đầu ra g occurs 2 times f occurs 1 times h occurs 1 times e occurs 1 times l occurs 2 times o occurs 1 times Cách tiếp cận-3. Trong cách tiếp cận này, chúng tôi sẽ sử dụng vòng lặp for để lặp qua chính chuỗi hoàn chỉnh. Đây là cách tiếp cận đơn giản nhất mà chúng tôi có thể thực hiện để tìm ra nhiệm vụ kết quả Làm cách nào để tìm tần suất của các ký tự trong một chuỗi trong JavaScript?tần suất của các ký tự trong chuỗi sử dụng đối tượng . for(let i=0;i
if(obj[str[i]]==không xác định) { obj[str[i]]=1; obj[str[i]]+=1; Làm cách nào để tìm các ký tự lặp lại trong một chuỗi trong JavaScript?+ (1 + n - (n-1)) = (n-1)*(1 + n) - (n)(n-1)/2 = (n^2 + n - 2) . Vì vậy, sẽ tốt hơn nếu sử dụng một đối tượng để lập bản đồ và ghi nhớ các ký tự để kiểm tra tính duy nhất hoặc trùng lặp . Giả sử kích thước dữ liệu tối đa cho mỗi ký tự, quy trình này sẽ là thuật toán O(n).
Làm cách nào để tìm ký tự được lặp lại nhiều nhất trong JavaScript?var exp = '355385' ; . tách ra(""); . độ dài;i++) {expCounts["_" + exps[i]] = (expCounts["_" + exps[i]]. 0) + 1 ;
Làm cách nào để tìm một ký tự cụ thể trong chuỗi JavaScript?Phương thức indexOf() trả về vị trí xuất hiện đầu tiên của một giá trị trong chuỗi. Phương thức indexOf() trả về -1 nếu không tìm thấy giá trị. Phương thức indexOf() phân biệt chữ hoa chữ thường. |