Question

How to find the first repeating element in an array of integers with TypeScript

Answer 1

function get_first_repeating_element(arr : any) {
    let min = -1;
  
    let set = new Set();
  
    for (let i = arr.length - 1; i >= 0; i--) {
        if (set.has(arr[i]))
            min = i;
        else
            set.add(arr[i]);
    }
  
    if (min != -1)
        return arr[min];
    else
        return -1;
}
 
const arr:number[] = [ 1, 2, 9, 5, 6, 5, 9, 3, 7 ];
 
console.log(get_first_repeating_element(arr));
 
 
   
   
   
   
/*
run:
   
9
   
*/

 

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