35 lines
702 B
C++
35 lines
702 B
C++
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#include <bits/stdc++.h>
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using namespace std;
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/**
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12345-->f(12345)=1*2^4+2*2^3+3*2^2+4*2^1+5*2^0
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f(1234) =1*2^3+2*2^2+3*2^1+4*2^0
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2*f(1234) =1*2^4+2*2^3+3*2^2+4*2^1
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所以形成递归表示式
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*/
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//利用递归计算出F(x)
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int f(int x) {
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if (x == 0) return 0;
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return f(x / 10) * 2 + x % 10;
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}
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//利用循环进行计算
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int f2(int x) {
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int res = 0;
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int i = 0;
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while (x) {
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res += x % 10 * (1 << i);
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i++;
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x /= 10;
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}
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return res;
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}
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int main() {
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cout << f(5) << endl;
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cout << f2(12345) << endl;
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//极大值是1e9-1=99999999
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cout << f2(1e9 - 1) << endl;
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//输出4599
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return 0;
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}
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