36 lines
850 B
C++
36 lines
850 B
C++
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#include <bits/stdc++.h>
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using namespace std;
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//手工版本的检查二进制中1的个数的办法
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int OneCount(int n) {
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int cnt = 0;
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for (int i = 31; i >= 0; i--)
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if ((n >> i) & 1) cnt++;//固定1，右移i大法好！
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return cnt;
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}
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int OneCount2(int n) {
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int cnt = 0;
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for (int i = 31; i >= 0; i--)
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if (n & (1 << i)) cnt++;//固定n，左移1大法好！
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return cnt;
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}
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int main() {
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int n;
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cin >> n;
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int cnt = __builtin_popcount(n);
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cout << "__builtin_popcount: cnt=" << cnt << endl;
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int cnt2 = OneCount(n);
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cout << "OneCount: cnt2=" << cnt2 << endl;
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int cnt3 = OneCount2(n);
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cout << "OneCount2: cnt3=" << cnt3 << endl;
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if (cnt == 1) cout << "是2的整数次幂！";
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else cout << "不是2的整数次幂！";
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return 0;
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}
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