C++ 程序用于计算可在给定条件下的图中进行的最大可能划分
假设我们有一个图 G 的邻接矩阵。我们必须检查是否可以将顶点划分为非空集合 V1、... Vk,以便:每条边连接属于两个相邻集合的两个顶点。如果答案是肯定的,我们必须在这样的划分中找出集合 k 的最大可能值。
因此,如果输入如下
0 | 1 | 0 | 1 | 1 | 0 |
1 | 0 | 1 | 0 | 0 | 1 |
0 | 1 | 0 | 1 | 0 | 0 |
1 | 0 | 1 | 0 | 0 | 0 |
1 | 0 | 0 | 0 | 0 | 0 |
0 | 1 | 0 | 0 | 0 | 0 |
则输出将为 4
步骤
为了解决这个问题,我们将遵循以下步骤 -
Define an array dp of size: 210. n := size of matrix fl := 1 ans := 0 for initialize i := 0, when i < n and fl is non-zero, update (increase i by 1), do: fill dp with -1 dp[i] := 0 Define one queue q insert i into q while (q is not empty), do: x := first element of q delete element from q for initialize j := 0, when j < n, update (increase j by 1), do: if matrix[x, j] is same as 1, then: if dp[j] is same as -1, then: dp[j] := dp[x] + 1 insert j into q otherwise when |dp[j] - dp[x]| is not equal to 1, then: fl := 0 for initialize j := 0, when j < n, update (increase j by 1), do: ans := maximum of ans and dp[j] if fl is same as 0, then: return -1 Otherwise return ans + 1
示例
让我们看看以下实现以获得更好的理解 -
#include <bits/stdc++.h> using namespace std; int solve(vector<vector<int>> matrix){ int dp[210]; int n = matrix.size(); int fl = 1; int ans = 0; for (int i = 0; i < n && fl; i++){ memset(dp, -1, sizeof(dp)); dp[i] = 0; queue<int> q; q.push(i); while (!q.empty()){ int x = q.front(); q.pop(); for (int j = 0; j < n; j++){ if (matrix[x][j] == 1){ if (dp[j] == -1){ dp[j] = dp[x] + 1; q.push(j); } else if (abs(dp[j] - dp[x]) != 1) fl = 0; } } } for (int j = 0; j < n; j++) ans = max(ans, dp[j]); } if (fl == 0){ return -1; }else{ return ans + 1; } } int main(){ vector<vector<int>> matrix = { { 0, 1, 0, 1, 1, 0 }, { 1, 0, 1, 0, 0, 1 }, { 0, 1, 0, 1, 0, 0 }, { 1, 0, 1, 0, 0, 0 }, { 1, 0, 0, 0, 0, 0 }, { 0, 1, 0, 0, 0, 0 } }; cout << solve(matrix) << endl; }
输入
{ { 0, 1, 0, 1, 1, 0 }, { 1, 0, 1, 0, 0, 1 }, { 0, 1, 0, 1, 0, 0 }, { 1, 0, 1, 0, 0, 0 }, { 1, 0, 0, 0, 0, 0 }, { 0, 1, 0, 0, 0, 0 } }
输出
4
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