Submission #1167848

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Source Code Expand

#include <stdio.h>

int main(){
  int x, l, r;
  scanf("%d", &x);
  l = 1;
  r = x+1;
  while(l + 1 < r){
    int y = (l & r) + (l ^ r) / 2;
    if((long long) y*(y+1)/2 < x) l = y+1;
    r = y;
  }
  if((long long) l*(l+1)/2 >= x) printf("%d\n", l);
  else printf("%d\n", l+1);
  return 0;
}

Submission Info

Judge Result