String Programs

let str="{{{{}}}}";
let end=str.length-2;
let start=1;
let temp;
let arr=[];

for(let i=0;i<str.length;i++){
      arr[i] = str[i]
    }
  while(start<end){

        temp=arr[start];
        arr[start]=arr[end];
        arr[end]=temp;
        start+=2;
        end-=2;


}
let result = "";
for (let i = 0; i < arr.length; i++) {
    result += arr[i];          // Fix 2: build result string
}
 console.log(result); 

let str="BBBBGGGG";
let end=str.length-2;
let start=1;
let temp;
let arr=[];

for(let i=0;i<str.length;i++){
      arr[i] = str[i]
    }
  while(start<end){

        temp=arr[start];
        arr[start]=arr[end];
        arr[end]=temp;
        start+=2;
        end-=2;


}
let result = "";
for (let i = 0; i < arr.length; i++) {
    result += arr[i];          // Fix 2: build result string
}
 console.log(result);

let sen = "";

let arr = [];

// convert string to array manually
for (let i = 0; i < sen.length; i++) {
    arr[i] = sen[i];
}

let left = 0;
let right = arr.length - 1;

function isVowel(ch) {
    return ch == 'a' ||
           ch == 'e' ||
           ch == 'i' ||
           ch == 'o' ||
           ch == 'u';
}

while (left < right) {

    while (left < right && !isVowel(arr[left])) {
        left++;
    }

    while (left < right && !isVowel(arr[right])) {
        right--;
    }

    // swap
    let temp = arr[left];
    arr[left] = arr[right];
    arr[right] = temp;

    left++;
    right--;
}

// print manually
let result = "";

for (let i = 0; i < arr.length; i++) {
    result = result + arr[i];
}

console.log(result);

str="a1b2c3d4";
result="";

for(let i=0;i<str.length;i=i+2){
  ch=str[i]

   let count = str[i + 1];

    for (let j = 0; j <= count; j++) {
        result = result + ch;
    }
}
console.log(result);

str="a1b2c3d4";
result="";

for(let i=0;i<str.length;i=i+2){
  ch=str[i]

   let count = str[i + 1];

    for (let j = 1; j <= count; j++) {
        result = result + ch;
    }
}
console.log(result);

et str = "abcd1234";

let result = "";

let mid = str.length / 2;

for (let i = 0; i < mid; i++) {

    result = result + str[i];

    result = result + str[mid + i];
}

console.log(result);