在给定字符串中倒排单词的 Javascript 程序
原文:https://www . geesforgeks . org/JavaScript-程序-给定字符串中的反向单词/
例:让输入字符串为“我很喜欢这个节目”。该函数应该将字符串更改为“非常像我这样的程序”
示例:
输入 : s =【极客问答练习代码】 输出 : s =【代码练习问答极客】
输入 : s =“擅长编码需要大量练习” 输出 : s =“擅长编码需要大量练习”
算法:
- 最初，逐个反转给定字符串的单个单词，对于上面的示例，反转单个单词后，字符串应该是“i ekil siht margorp yrev hcum”。
- 从头到尾反转整个字符串得到想要的输出“非常像我这个程序”在上例中。
下面是上述方法的实现:
java 描述语言
<script>
// Javascript program to reverse
// a String
// Reverse the letters of
// the word
function reverse(str, start, end)
{
// Temporary variable to
// store character
let temp;
while (start <= end)
{
// Swapping the first and
// last character
temp = str[start];
str[start] = str[end];
str[end] = temp;
start++;
end--;
}
}
// Function to reverse words
function reverseWords(s)
{
// Reversing individual words as
// explained in the first step
s = s.split("");
let start = 0;
for (let end = 0;
end < s.length; end++)
{
// If we see a space, we reverse
// the previous word (word between
// the indexes start and end-1
// i.e., s[start..end-1]
if (s[end] == ' ')
{
reverse(s, start, end);
start = end + 1;
}
}
// Reverse the last word
reverse(s, start, s.length - 1);
// Reverse the entire String
reverse(s, 0, s.length - 1);
return s.join("");
}
// Driver Code
var s =
"i like this program very much ";
document.write(reverseWords(s));
// This code is contributed by avanitrachhadiya2155
</script>
输出:
much very program this like i
另一种方法:
我们可以通过以相反的方式拆分和保存字符串来完成上述任务。
下面是上述方法的实现:
java 描述语言
<script>
// JavaScript program to reverse a string
var s = ["i", "like", "this",
"program", "very", "much"];
var ans ="";
for (var i = 5; i >= 0; i--)
{
ans += s[i] + " ";
}
document.write(
"Reversed String:"+ "<br>");
document.write(
ans.slice(0,ans.length-1));
</script>
输出:
Reversed String:
much very program this like i
时间复杂度: O(n)
不使用任何额外空间: 以上任务也可以从中间开始拆分直接对换字符串来完成。由于涉及直接交换，因此占用的空间也更少。
下面是上述方法的实现:
java 描述语言
<script>
// Javascript code to reverse a string
// Reverse the string
function RevString(s, l)
{
// Check if number of words
// is even
if (l % 2 == 0)
{
// Find the middle word
let j = parseInt(l / 2, 10);
// Starting from the middle start
// swapping words at jth position
// and l-1-j position
while (j <= l - 1)
{
let temp;
temp = s[l - j - 1];
s[l - j - 1] = s[j];
s[j] = temp;
j += 1;
}
}
// Check if number of words is odd
else
{
// Find the middle word
let j = parseInt((l / 2), 10) + 1;
// Starting from the middle start
// swapping the words at jth
// position and l-1-j position
while (j <= l - 1)
{
let temp;
temp = s[l - j - 1];
s[l - j - 1] = s[j];
s[j] = temp;
j += 1;
}
}
let S = s[0];
// Return the reversed sentence
for(let i = 1; i < 9; i++)
{
S = S + " " + s[i];
}
return S;
}
// Driver code
let s = "getting good at coding "
"needs a lot of practice";
let words = ["getting", "good", "at",
"coding", "needs", "a",
"lot", "of", "practice"];
document.write(RevString(words, 9));
// This code is contributed by suresh07
</script>
输出:
practice of lot a needs coding at good getting
更多详情请参考给定字符串倒字整篇文章！
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