find missing number from an array
only one
by aninaslyan
JavaScript
function missing(A) {
let s=0
n=A.length
total=(n+1)*(n+2)/2
for(let i=0;i<n;i++) {
s+=A[i]
}
return total - sJ
}
let A = [1, 2, 4, 5, 6, 7, 8, 9]
z = missing(A)
alert(z)