64 lines
1.5 KiB
C++
64 lines
1.5 KiB
C++
#include<bits/stdc++.h>
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using namespace std;
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const int N = 10;
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int a[N], cnt;
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//求反数：数位分离数字，然后想办法再级成大数字
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void FanShu_ShuWeiFenLi(int x) {
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int t = x;
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//数位分离到一个数组中
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//12345--->[5,4,3,2,1]=5*10000+4*1000+3*100+2*10+1*1=54321
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while (t) {
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int m = t % 10;
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a[cnt++]= m;
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t /= 10;
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}
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//打印出这个数组
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for (int i = 0; i < cnt; i++)cout << a[i];
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//方法（1）：通过数学公式pow拼成一个大数字
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int ans = 0;
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//5,4,3,2,1=5*10000
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//10^4
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//cnt=5
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//cnt-1
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//cnt-i-1
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for (int i = 0; i < cnt; i++)
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ans += a[i] * pow(10, cnt - i - 1);
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//分析一下为什么是cnt-i-1
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cout << ans << endl;
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//方法（2)：利用频繁的累乘方式拼成一个大数字
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ans = 0;//12345-->54321
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//5*10=50--+4>54
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//54*10=540+3=543
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//543*10=5430+2=5432
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//5432*10+1=54321
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for (int i = 0; i < cnt; i++)
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ans = ans * 10 + a[i];
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cout << ans << endl;
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//方法（3）:利用字符串转换
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string s = "";
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for (int i = 0; i < cnt; i++) s += to_string(a[i]);
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cout << s << endl;
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}
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//利用原始字符串反转进行
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void FanShu_ByString(int x) {
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string a = to_string(x);
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reverse(a.begin(), a.end());
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cout << a << endl;
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}
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int main() {
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//测试一个数字
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FanShu_ShuWeiFenLi(12345);
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//利用原始字符串反转进行
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FanShu_ByString(12345);
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return 0;
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}
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