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refactor 174
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‎src/main/java/com/fishercoder/solutions/_174.java‎

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import com.fishercoder.common.utils.CommonUtils;
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/**174. Dungeon Game
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/**
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* 174. Dungeon Game
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The demons had captured the princess (P) and imprisoned her in the bottom-right corner of a dungeon. The dungeon consists of m x N rooms laid out in a 2D grid. Our valiant knight (K) was initially positioned in the top-left room and must fight his way through the dungeon to rescue the princess.
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The demons had captured the princess (P) and imprisoned her in the bottom-right corner of a dungeon. The dungeon consists of M x N rooms laid out in a 2D grid. Our valiant knight (K) was initially positioned in the top-left room and must fight his way through the dungeon to rescue the princess.
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The knight has an initial health point represented by a positive integer. If at any point his health point drops to 0 or below, he dies immediately.
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The knight has an initial health point represented by a positive integer. If at any point his health point drops to 0 or below, he dies immediately.
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Some of the rooms are guarded by demons, so the knight loses health (negative integers) upon entering these rooms; other rooms are either empty (0's) or contain magic orbs that increase the knight's health (positive integers).
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Some of the rooms are guarded by demons, so the knight loses health (negative integers) upon entering these rooms; other rooms are either empty (0's) or contain magic orbs that increase the knight's health (positive integers).
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In order to reach the princess as quickly as possible, the knight decides to move only rightward or downward in each step.
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In order to reach the princess as quickly as possible, the knight decides to move only rightward or downward in each step.
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Write a function to determine the knight's minimum initial health so that he is able to rescue the princess.
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Write a function to determine the knight's minimum initial health so that he is able to rescue the princess.
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For example, given the dungeon below, the initial health of the knight must be at least 7 if he follows the optimal path RIGHT-> RIGHT -> DOWN -> DOWN.
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-2 (K) -3 3
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-5 -10 1
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10 30 -5 (P)
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For example, given the dungeon below, the initial health of the knight must be at least 7 if he follows the optimal path RIGHT-> RIGHT -> DOWN -> DOWN.
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-2 (K) -3 3
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-5 -10 1
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10 30 -5 (P)
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Notes:
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Note:
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The knight's health has no upper bound.
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Any room can contain threats or power-ups, even the first room the knight enters and the bottom-right room where the princess is imprisoned.
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The knight's health has no upper bound.
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Any room can contain threats or power-ups, even the first room the knight enters and the bottom-right room where the princess is imprisoned.
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*/
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public class _174 {
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/**This problem should fill the dp matrix from bottom right.*/
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public int calculateMinimumHP(int[][] dungeon) {
31-
if (dungeon == null || dungeon.length == 0) {
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return 0;
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}
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int height = dungeon.length;
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int width = dungeon[0].length;
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int[][] dp = new int[height][width];
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dp[height - 1][width - 1] = (dungeon[height - 1][width - 1] > 0) ? 1 : 1 - dungeon[height - 1][width - 1];
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//fill the last column
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for (int i = height - 2; i >= 0; i--) {
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int temp = dp[i + 1][width - 1] - dungeon[i][width - 1];
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dp[i][width - 1] = Math.max(1, temp);
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}
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46-
//fill the last row
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public static class Solution1 {
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/** This problem should fill the dp matrix from bottom right. */
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public int calculateMinimumHP(int[][] dungeon) {
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if (dungeon == null || dungeon.length == 0) {
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return 0;
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}
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int height = dungeon.length;
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int width = dungeon[0].length;
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int[][] dp = new int[height][width];
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dp[height - 1][width - 1] =
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(dungeon[height - 1][width - 1] > 0) ? 1 : 1 - dungeon[height - 1][width - 1];
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//fill the last column
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for (int i = height - 2; i >= 0; i--) {
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int temp = dp[i + 1][width - 1] - dungeon[i][width - 1];
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dp[i][width - 1] = Math.max(1, temp);
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}
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//fill the last row
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for (int j = width - 2; j >= 0; j--) {
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int temp = dp[height - 1][j + 1] - dungeon[height - 1][j];
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dp[height - 1][j] = Math.max(temp, 1);
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}
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for (int i = height - 2; i >= 0; i--) {
4757
for (int j = width - 2; j >= 0; j--) {
48-
int temp = dp[height - 1][j + 1] - dungeon[height - 1][j];
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dp[height - 1][j] = Math.max(temp, 1);
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}
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for (int i = height - 2; i >= 0; i--) {
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for (int j = width - 2; j >= 0; j--) {
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int down = Math.max(1, dp[i + 1][j] - dungeon[i][j]);
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int right = Math.max(1, dp[i][j + 1] - dungeon[i][j]);
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dp[i][j] = Math.min(down, right);
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}
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}
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CommonUtils.printMatrix(dp);
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return dp[0][0];
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}
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public static void main(String... strings) {
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_174 test = new _174();
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// int[][] dungeon = new int[1][1];
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// dungeon[0][0] = 0;
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// int[][] dungeon = new int[1][1];
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// dungeon[0][0] = -200;
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// int[][] dungeon = new int[1][2];
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// dungeon[0][0] = 0;
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// dungeon[0][1] = -3;
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// int[][] dungeon = new int[2][1];
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// dungeon[0][0] = -3;
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// dungeon[1][0] = -7;
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int[][] dungeon = new int[2][1];
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dungeon[0][0] = 2;
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dungeon[1][0] = 1;
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// int[][] dungeon = new int[1][2];
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// dungeon[0][0] = -3;
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// dungeon[0][1] = 5;
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// int[][] dungeon = new int[2][2];
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// dungeon[0][0] = 2;
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// dungeon[0][1] = 1;
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// dungeon[1][0] = 1;
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// dungeon[1][1] = -1;
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// int[][] dungeon = new int[1][2];
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// dungeon[0][0] = 0;
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// dungeon[0][1] = 0;
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// int[][] dungeon = new int[2][1];
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// dungeon[0][0] = 0;
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// dungeon[1][0] = 0;
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// int[][] dungeon = new int[3][3];
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// dungeon[0][0] = -2;
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// dungeon[0][1] = -3;
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// dungeon[0][2] = 3;
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// dungeon[1][0] = -5;
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// dungeon[1][1] = -10;
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// dungeon[1][2] = 1;
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// dungeon[2][0] = 10;
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// dungeon[2][1] = 30;
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// dungeon[2][2] = -5;
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// int[][] dungeon = new int[2][3];
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// dungeon[0][0] = 0;
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// dungeon[0][1] = 0;
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// dungeon[0][2] = 0;
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// dungeon[1][0] = 1;
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// dungeon[1][1] = 1;
120-
// dungeon[1][2] = -1;
121-
CommonUtils.printMatrix(dungeon);
122-
System.out.println(test.calculateMinimumHP(dungeon));
123-
}
124-
125-
public int calculateMinimumHP_attemp2_failed(int[][] dungeon) {
126-
if (dungeon == null || dungeon.length == 0) {
127-
return 0;
128-
}
129-
130-
int height = dungeon.length;
131-
int width = dungeon[0].length;
132-
int[][] dp = new int[height][width];
133-
dp[0][0] = dungeon[0][0] > 0 ? 1 : 1 - dungeon[0][0];
134-
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//fill the first column
136-
for (int i = 1; i < height; i++) {
137-
dp[i][0] = dungeon[i][0] >= 0 ? dp[i - 1][0] : -dungeon[i][0] + dp[i - 1][0];
138-
}
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//fill the first row
141-
for (int j = 1; j < width; j++) {
142-
dp[0][j] = dungeon[0][j] >= 0 ? dp[0][j - 1] : -dungeon[0][j] + dp[0][j - 1];
143-
}
144-
145-
for (int i = 1; i < height; i++) {
146-
for (int j = 1; j < width; j++) {
147-
dp[i][j] = dungeon[i][j] >= 0 ? Math.min(dp[i][j - 1], dp[i - 1][j]) : -dungeon[i][j] + Math.min(dp[i][j - 1], dp[i - 1][j]);
148-
}
58+
int down = Math.max(1, dp[i + 1][j] - dungeon[i][j]);
59+
int right = Math.max(1, dp[i][j + 1] - dungeon[i][j]);
60+
dp[i][j] = Math.min(down, right);
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}
62+
}
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151-
CommonUtils.printMatrix(dp);
152-
return dp[height - 1][width - 1];
64+
CommonUtils.printMatrix(dp);
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return dp[0][0];
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}
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}
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}

‎src/test/java/com/fishercoder/_174Test.java‎

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package com.fishercoder;
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import com.fishercoder.solutions._174;
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import org.junit.BeforeClass;
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import org.junit.Test;
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7+
import static org.junit.Assert.assertEquals;
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public class _174Test {
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private static _174.Solution1 solution1;
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private int[][] dungeon;
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@BeforeClass
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public static void setup() {
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solution1 = new _174.Solution1();
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}
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18+
@Test
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public void test1() {
20+
dungeon = new int[][] {
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{0}
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};
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assertEquals(1, solution1.calculateMinimumHP(dungeon));
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}
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@Test
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public void test2() {
28+
dungeon = new int[][] {
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{-200}
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};
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assertEquals(201, solution1.calculateMinimumHP(dungeon));
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}
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}

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