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77 lines
2.1 KiB
77 lines
2.1 KiB
package class22;
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import java.util.PriorityQueue;
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// 本题测试链接 : https://leetcode.com/problems/trapping-rain-water-ii/
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public class Code03_TrappingRainWaterII {
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public static class Node {
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public int value;
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public int row;
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public int col;
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public Node(int v, int r, int c) {
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value = v;
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row = r;
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col = c;
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}
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}
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public static int trapRainWater(int[][] heightMap) {
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if (heightMap == null || heightMap.length == 0 || heightMap[0] == null || heightMap[0].length == 0) {
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return 0;
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}
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int N = heightMap.length;
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int M = heightMap[0].length;
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boolean[][] isEnter = new boolean[N][M];
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PriorityQueue<Node> heap = new PriorityQueue<>((a, b) -> a.value - b.value);
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for (int col = 0; col < M - 1; col++) {
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isEnter[0][col] = true;
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heap.add(new Node(heightMap[0][col], 0, col));
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}
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for (int row = 0; row < N - 1; row++) {
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isEnter[row][M - 1] = true;
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heap.add(new Node(heightMap[row][M - 1], row, M - 1));
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}
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for (int col = M - 1; col > 0; col--) {
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isEnter[N - 1][col] = true;
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heap.add(new Node(heightMap[N - 1][col], N - 1, col));
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}
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for (int row = N - 1; row > 0; row--) {
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isEnter[row][0] = true;
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heap.add(new Node(heightMap[row][0], row, 0));
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}
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int water = 0;
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int max = 0;
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while (!heap.isEmpty()) {
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Node cur = heap.poll();
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max = Math.max(max, cur.value);
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int r = cur.row;
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int c = cur.col;
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if (r > 0 && !isEnter[r - 1][c]) {
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water += Math.max(0, max - heightMap[r - 1][c]);
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isEnter[r - 1][c] = true;
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heap.add(new Node(heightMap[r - 1][c], r - 1, c));
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}
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if (r < N - 1 && !isEnter[r + 1][c]) {
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water += Math.max(0, max - heightMap[r + 1][c]);
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isEnter[r + 1][c] = true;
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heap.add(new Node(heightMap[r + 1][c], r + 1, c));
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}
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if (c > 0 && !isEnter[r][c - 1]) {
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water += Math.max(0, max - heightMap[r][c - 1]);
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isEnter[r][c - 1] = true;
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heap.add(new Node(heightMap[r][c - 1], r, c - 1));
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}
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if (c < M - 1 && !isEnter[r][c + 1]) {
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water += Math.max(0, max - heightMap[r][c + 1]);
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isEnter[r][c + 1] = true;
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heap.add(new Node(heightMap[r][c + 1], r, c + 1));
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}
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}
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return water;
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}
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}
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