std::array<double, 6> binsx{0, 5, 10, 20, 50, 100};
TH1F *orig = new TH1F("orig", "Original histogram before normalization", binsx.size() - 1, &binsx[0]);

gStyle->SetTitleFontSize(0.06);

TRandom2 rand;

for (int i = 0; i < 100'000; ++i) {
   double r = rand.Rndm() * 100;
   orig->Fill(r);
}

TH1F *norm = (TH1F *)orig->Clone("norm");
norm->SetTitle("Normalized Histogram");

norm->Scale(1. / norm->Integral(), "width");

TCanvas *c1 = new TCanvas("c1", "Histogram Normalization", 700, 900);
c1->Divide(1, 2);

c1->cd(1);
orig->Draw();
c1->cd(2);
norm->Draw();

%jsroot on
gROOT->GetListOfCanvases()->Draw()