arifin_fuad_kashfy's blog

how my code got ac
By arifin_fuad_kashfy, history, 17 hours ago, In English

hellow, cf frined

u can go to my submission and check the last problem c in my submission, that has got ac, but how idk. Can anyone explain the right approach

I go to google;s xor calculator and input some values, find a pattern, and implement it with a random guess , and it has got AC :)

pls help,

Thanks in advance.:) here is it how it passed

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17 hours ago, # |
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x-1 to 1??

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    15 hours ago, # ^ |
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    nah vai oitha test er jonow contest shese didis contest time e aktha ac hosisilow ar age dharan link dei Your text to link here...

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16 hours ago, # |
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if you know binary search, it was simple simulation, i dont know why so many people were worried to make bitwise operations on that!

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    4 hours ago, # ^ |
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    how do you show monotonicity on the range of y?

    thanks

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      3 hours ago, # ^ |
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      it was said y would lie from 1 to x-1, so that is our range, then we will check for mid, and see if x^mid < x+mid and x^mid > x-mid, if both conditions are satisfied it is a valid y, so print it, think about it, is much easier than what others did

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15 hours ago, # |
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Auto comment: topic has been updated by arifin_fuad_kashfy (previous revision, new revision, compare).

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3 hours ago, # |
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what is "__builtin_clz(x)": This counts the number of leading zeros in the binary representation of x.

eg:

If x = 5 (binary 101), the number of leading zeros is 29 (assuming a 32-bit integer, since 5 is 000xxx000101).

If x = 8 (binary 1000), the number of leading zeros is 28.

If x = 5 (binary 101), 32 — __builtin_clz(5) — 1 = 3 — 1 = 2.

If x = 8 (binary 1000), 32 — __builtin_clz(8) — 1 = 4 — 1 = 3.

TRY THIS CODE-->


#include <bits/stdc++.h>
using namespace std;
#define ll long long
int binary_of_x(int x) {
    return (1 << (32 &mdash; __builtin_clz(x) &mdash; 1)) &mdash; 1;
}

void solve() 
{
    ll x;
    cin >> x;
    ll B = binary_of_x(x);
    ll xorB = x ^ B;
    ll a = B, b = xorB, c = x;
    if (a > c) {
    	swap(a, c);
    }
    if (b > c){ 
    	swap(b, c);
    	
    }
    if (a + b > c) {
        cout << B << "\n";
    } else {
        cout << "-1\n";
    }
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t;
    cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}
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