38 lines
956 B
Java
38 lines
956 B
Java
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public class SteinerTree {
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public static int minLengthSteinerTree(int[][] g, int[] verticesToConnect) {
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int n = g.length;
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int m = verticesToConnect.length;
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if (m <= 1)
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return 0;
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for (int k = 0; k < n; k++)
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for (int i = 0; i < n; i++)
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for (int j = 0; j < n; j++)
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g[i][j] = Math.min(g[i][j], g[i][k] + g[k][j]);
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int[][] dp = new int[1 << m][n];
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for (int i = 0; i < m; i++)
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for (int j = 0; j < n; j++)
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dp[1 << i][j] = g[verticesToConnect[i]][j];
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for (int i = 1; i < 1 << m; i++) {
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if (((i - 1) & i) != 0) {
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for (int j = 0; j < n; j++) {
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dp[i][j] = Integer.MAX_VALUE / 2;
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for (int k = (i - 1) & i; k > 0; k = (k - 1) & i) {
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dp[i][j] = Math.min(dp[i][j], dp[k][j] + dp[i ^ k][j]);
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}
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}
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for (int j = 0; j < n; j++) {
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for (int k = 0; k < n; k++) {
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dp[i][j] = Math.min(dp[i][j], dp[i][k] + g[k][j]);
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}
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}
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}
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}
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return dp[(1 << m) - 1][verticesToConnect[0]];
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}
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}
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