50 lines
1.1 KiB
C++
50 lines
1.1 KiB
C++
#include <bits/stdc++.h>
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using namespace std;
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const int N = 5010;
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/**
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* 功能：高精度加法模板
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* @param A
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* @param B
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* @return
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*/
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vector<int> add(vector<int> &A, vector<int> &B) {
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if (A.size() < B.size()) return add(B, A);
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int t = 0;
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vector<int> C;
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for (int i = 0; i < A.size(); i++) {
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t += A[i];
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if (i < B.size()) t += B[i];
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C.push_back(t % 10);
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t /= 10;
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}
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if (t) C.push_back(t);
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return C;
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}
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vector<int> A, B, C;
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int main() {
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int n;
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cin >> n;
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if (n <= 2) {
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printf("%d", n);
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return 0;
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}
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//初始化一阶台阶步数
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A.push_back(1);
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//初始化二阶台阶步数
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B.push_back(2);
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//以后每阶台阶，都是可以从i-1,i-2阶台阶迁移过来，方法数就是两者的和
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for (int i = 3; i <= n; i++) {
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C = add(A, B);
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//A<---B 方便下次计算
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A.assign(B.begin(), B.end());
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//B<---C 方便下次计算
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B.assign(C.begin(), C.end());
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}
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//倒序输出结果
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for (int i = B.size() - 1; i >= 0; i--)
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printf("%d", B[i]);
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return 0;
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} |