43 lines
853 B
Java
43 lines
853 B
Java
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public class RmqSparseTable {
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int[] logTable;
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int[][] rmq;
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int[] a;
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public RmqSparseTable(int[] a) {
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this.a = a;
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int n = a.length;
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logTable = new int[n + 1];
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for (int i = 2; i <= n; i++)
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logTable[i] = logTable[i >> 1] + 1;
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rmq = new int[logTable[n] + 1][n];
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for (int i = 0; i < n; ++i)
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rmq[0][i] = i;
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for (int k = 1; (1 << k) < n; ++k) {
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for (int i = 0; i + (1 << k) <= n; i++) {
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int x = rmq[k - 1][i];
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int y = rmq[k - 1][i + (1 << k - 1)];
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rmq[k][i] = a[x] <= a[y] ? x : y;
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}
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}
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}
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public int minPos(int i, int j) {
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int k = logTable[j - i];
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int x = rmq[k][i];
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int y = rmq[k][j - (1 << k) + 1];
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return a[x] <= a[y] ? x : y;
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}
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public static void main(String[] args) {
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int[] a = { 1, 5, -2, 3 };
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RmqSparseTable st = new RmqSparseTable(a);
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System.out.println(2 == st.minPos(0, 3));
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}
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}
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