weekly contest 302

Author: ZLBer

README.md

@@ -4,6 +4,8 @@ Record leetcode contest and ideas every week, and encourage yourself to think mo
 
 leetcode url: <https://leetcode.cn/u/cctest/>
 
+
+* ☀️ [weekly contest 302](src/main/java/weekly/wk302.java)     Array |   Heap | Heap| Math GCD
 * ☀️ [weekly contest 301](src/main/java/weekly/wk301.java)     Greegy |   Hash Table | Two Pointers|Dynamic Programming+Combinatorics
 * ☀️ [weekly contest 300](src/main/java/weekly/wk300.java)     Hash Table | Simulation | DP | DP
 * ☔ [weekly contest 299](src/main/java/weekly/wk299.java)     Array |  DP | DP  | Enumeration + classification discussion

src/main/java/weekly/wk302.java

@@ -0,0 +1,117 @@
+package weekly;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.PriorityQueue;
+
+public class wk302 {
+
+    //ranking: 445 / 7092
+
+    //Array
+    //简单题，统计每个数字出现多少次就行
+    public int[] numberOfPairs(int[] nums) {
+        int[] res = new int[2];
+        int count[] = new int[102];
+        for (int c : nums) {
+            count[c]++;
+        }
+        for (int i : count) {
+            res[0] += i / 2;
+            res[1] += i % 2;
+        }
+        return res;
+    }
+
+    //Heap
+    //中等题，将数位和相同的放在一个优先队列中，弹出最大的两个
+    public int maximumSum(int[] nums) {
+        Map<Integer, PriorityQueue<Integer>> map = new HashMap<>();
+        for (int num : nums) {
+            int c = num;
+            int sum = 0;
+            while (num > 0) {
+                sum += num % 10;
+                num /= 10;
+            }
+            if (!map.containsKey(sum)) {
+                map.put(sum, new PriorityQueue<>(Comparator.reverseOrder()));
+            }
+            map.get(sum).add(c);
+        }
+        int ans = -1;
+        for (Map.Entry<Integer, PriorityQueue<Integer>> entry : map.entrySet()) {
+            if (entry.getValue().size() < 2) continue;
+            int max = entry.getValue().poll() + entry.getValue().poll();
+            ans = Math.max(ans, max);
+        }
+        return ans;
+    }
+
+    class help {
+        String value;
+        int index;
+
+        help(String v, int i) {
+            value = v;
+            index = i;
+        }
+    }
+    //Heap
+    //中等题，先把所有的剪裁结果都保存下来，然后取第k个即可
+    public int[] smallestTrimmedNumbers(String[] nums, int[][] queries) {
+        int m = nums[0].length();
+        Map<Integer, List<help>> map = new HashMap<>();
+        for (int i = 0; i < m; i++) {
+            List<help> list = new ArrayList<>();
+            for (int j = 0; j < nums.length; j++) {
+                String substring = nums[j].substring(i);
+                list.add(new help(substring, j));
+            }
+            map.put(nums[0].length() - i, list);
+        }
+
+        for (List<help> value : map.values()) {
+            Collections.sort(value, (a, b) -> a.value.compareTo(b.value));
+        }
+
+
+        int[] res = new int[queries.length];
+        for (int i = 0; i < queries.length; i++) {
+            int[] query = queries[i];
+            List<help> list = map.get(query[1]);
+
+            res[i] = list.get(query[0] - 1).index;
+        }
+        return res;
+    }
+
+    private static long gcd2(long a, long b) {
+        return (a == 0 ? b : gcd2(b % a, a));
+    }
+
+    //MATH
+    //困难提不困难，求numsDivide的最大公因数，nums从小往大遍历，看哪个能整除即可
+    public int minOperations(int[] nums, int[] numsDivide) {
+        Arrays.sort(nums);
+
+        int pre = numsDivide[0];
+        for (int i = 0; i < numsDivide.length; i++) {
+            pre = (int) gcd2(pre, numsDivide[i]);
+        }
+        for (int i = 0; i < nums.length; i++) {
+          if(pre%nums[i]==0) return i;
+        }
+        return -1;
+    }
+
+    public static void main(String[] args) {
+
+    }
+
+}