// For the below algorithm, calculate the exact number of times   // System.out.println statement is executed as a function of n. Assume n≥1    for (int i=0; i<=n; i++) {    for (int j = i; j < 2*n; j++) {    System.out. println(”1 iteration executed!”);    }    }這是解決方案，但我很難理解數(shù)學(xué)。Overall RT = 2n + (2n-1) + (2n-2) + … + n = = (n+1)*n + (n+(n-1)+(n-2)+…+1+0) = = n2 + n + n*(n+1)/2 = = 1.5*n2 + 1.5n