add 1341

fishercoder1534 · fishercoder1534 · commit 857c359c3335 · 2020-02-02T08:30:32.000-08:00
diff --git a/README.md b/README.md
@@ -9,6 +9,7 @@ _If you like this project, please leave me a star._ &#9733;
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|--------|-------------|-------------
 |1343|[Maximum Product of Splitted Binary Tree](https://leetcode.com/problems/maximum-product-of-splitted-binary-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1343.java) | |Medium||
+|1341|[The K Weakest Rows in a Matrix](https://leetcode.com/problems/the-k-weakest-rows-in-a-matrix/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1341.java) | |Easy||
 |1333|[Filter Restaurants by Vegan-Friendly, Price and Distance](https://leetcode.com/problems/filter-restaurants-by-vegan-friendly-price-and-distance/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1333.java) | |Medium||
 |1331|[Rank Transform of an Array](https://leetcode.com/problems/rank-transform-of-an-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1331.java) | |Easy||
 |1329|[Sort the Matrix Diagonally](https://leetcode.com/problems/sort-the-matrix-diagonally/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1329.java) | |Medium||
diff --git a/src/main/java/com/fishercoder/solutions/_1341.java b/src/main/java/com/fishercoder/solutions/_1341.java
@@ -0,0 +1,81 @@
+package com.fishercoder.solutions;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * 1341. The K Weakest Rows in a Matrix
+ *
+ * Given a m * n matrix mat of ones (representing soldiers) and zeros (representing civilians),
+ * return the indexes of the k weakest rows in the matrix ordered from the weakest to the strongest.
+ * A row i is weaker than row j, if the number of soldiers in row i is less than the number of soldiers in row j,
+ * or they have the same number of soldiers but i is less than j. Soldiers are always stand in the frontier of a row,
+ * that is, always ones may appear first and then zeros.
+ *
+ * Example 1:
+ * Input: mat =
+ * [[1,1,0,0,0],
+ *  [1,1,1,1,0],
+ *  [1,0,0,0,0],
+ *  [1,1,0,0,0],
+ *  [1,1,1,1,1]],
+ * k = 3
+ * Output: [2,0,3]
+ * Explanation:
+ * The number of soldiers for each row is:
+ * row 0 -> 2
+ * row 1 -> 4
+ * row 2 -> 1
+ * row 3 -> 2
+ * row 4 -> 5
+ * Rows ordered from the weakest to the strongest are [2,0,3,1,4]
+ *
+ * Example 2:
+ * Input: mat =
+ * [[1,0,0,0],
+ *  [1,1,1,1],
+ *  [1,0,0,0],
+ *  [1,0,0,0]],
+ * k = 2
+ * Output: [0,2]
+ * Explanation:
+ * The number of soldiers for each row is:
+ * row 0 -> 1
+ * row 1 -> 4
+ * row 2 -> 1
+ * row 3 -> 1
+ * Rows ordered from the weakest to the strongest are [0,2,3,1]
+ *
+ * Constraints:
+ * m == mat.length
+ * n == mat[i].length
+ * 2 <= n, m <= 100
+ * 1 <= k <= m
+ * matrix[i][j] is either 0 or 1.
+ * */
+public class _1341 {
+    public static class Solution1 {
+        public int[] kWeakestRows(int[][] mat, int k) {
+            List<int[]> list = new ArrayList<>();
+            for (int i = 0; i < mat.length; i++) {
+                int soldiers = 0;
+                for (int j = 0; j < mat[0].length; j++) {
+                    if (mat[i][j] == 1) {
+                        soldiers++;
+                    } else {
+                        break;
+                    }
+                }
+                list.add(new int[]{i, soldiers});
+            }
+            Collections.sort(list, (a, b) -> a[1] == b[1] ? a[0] - b[0] : a[1] - b[1]);
+            int[] result = new int[k];
+            int i = 0;
+            while (i < k) {
+                result[i] = list.get(i++)[0];
+            }
+            return result;
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_1341Test.java b/src/test/java/com/fishercoder/_1341Test.java
@@ -0,0 +1,41 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1341;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertArrayEquals;
+
+public class _1341Test {
+    private static _1341.Solution1 solution1;
+    private static int[][] mat;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1341.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        mat = new int[][]{
+                {1, 1, 0, 0, 0},
+                {1, 1, 1, 1, 0},
+                {1, 0, 0, 0, 0},
+                {1, 1, 0, 0, 0},
+                {1, 1, 1, 1, 1}
+        };
+        assertArrayEquals(new int[]{2, 0}, solution1.kWeakestRows(mat, 2));
+    }
+
+    @Test
+    public void test2() {
+        mat = new int[][]{
+                {1, 0, 0, 0},
+                {1, 1, 1, 1},
+                {1, 0, 0, 0},
+                {1, 0, 0, 0}
+        };
+        assertArrayEquals(new int[]{0, 2}, solution1.kWeakestRows(mat, 2));
+    }
+
+}
