最大化C++中长度为p、q和r的线段数量
问题陈述
给定一根长度为L的杆,任务是将杆切割成若干段,使得长度为p、q和r的线段总数最大化。线段长度只能为p、q和r。
如果l = 15,p = 2,q = 3,r = 5,则可以得到如下7段:
{2, 2, 2, 2, 2, 2, 3}
算法
我们可以使用动态规划来解决这个问题。
1. Initialize dp[] array to 0 2. Iterate till the length of the rod. For every i, a cut of p, q and r if possible is done. 3. Initialize ans[i+p] = max( ans[i+p], 1 + ans[i]), ans[i+q] = max(ans[i+q], 1 + ans[i]) and ans[i+r] = max(ans[i+r], 1 + ans[i]) for all the possible cuts. 4. ans[i] will be 0 if a cut at i-th index is not possible. ans[l] will give the maximum number of cuts possible
示例
#include <bits/stdc++.h> using namespace std; int getMaximumSegments(int l, int p, int q, int r){ int dp[l + 1]; memset(dp, -1, sizeof(dp)); dp[0] = 0; for (int i = 0; i <= l; ++i) { if (dp[i] == -1) { continue; } if (i + p <= l) { dp[i + p] = max(dp[i + p], dp[i] + 1); } if (i + q <= l) { dp[i + q] = max(dp[i + q], dp[i] + 1); } if (i + r <= l) { dp[i + r] = max(dp[i + r], dp[i] + 1); } } return dp[l]; } int main(){ int l = 15, p = 2, q = 3, r = 5; cout << "Number of segments = " << getMaximumSegments(l, p, q, r) << endl; return 0; }
输出
编译并运行上述程序后,会生成以下输出:
Number of segments = 7
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