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| 1 | +package weekly; |
| 2 | + |
| 3 | +import java.util.ArrayDeque; |
| 4 | +import java.util.ArrayList; |
| 5 | +import java.util.Arrays; |
| 6 | +import java.util.Collections; |
| 7 | +import java.util.HashMap; |
| 8 | +import java.util.HashSet; |
| 9 | +import java.util.List; |
| 10 | +import java.util.Map; |
| 11 | +import java.util.Set; |
| 12 | +import java.util.TreeMap; |
| 13 | + |
| 14 | +public class wk364 { |
| 15 | + |
| 16 | + //贪心 |
| 17 | + public String maximumOddBinaryNumber(String s) { |
| 18 | + int count = 0; |
| 19 | + for (int i = 0; i < s.length(); i++) { |
| 20 | + if (s.charAt(i) == '1') { |
| 21 | + count++; |
| 22 | + } |
| 23 | + } |
| 24 | + char[] ans = new char[s.length()]; |
| 25 | + |
| 26 | + count--; |
| 27 | + for (int i = 0; i < ans.length; i++) { |
| 28 | + if (count > 0) { |
| 29 | + count--; |
| 30 | + ans[i] = '1'; |
| 31 | + } else { |
| 32 | + ans[i] = '0'; |
| 33 | + } |
| 34 | + } |
| 35 | + ans[ans.length - 1] = '1'; |
| 36 | + return new String(ans); |
| 37 | + } |
| 38 | + |
| 39 | + |
| 40 | + /* public long maximumSumOfHeights(List<Integer> maxHeights) { |
| 41 | + long res = 0; |
| 42 | + for (int i = 0; i < maxHeights.size(); i++) { |
| 43 | + long ans = maxHeights.get(i); |
| 44 | + int pre = maxHeights.get(i); |
| 45 | + for (int j = i - 1; j >= 0; j--) { |
| 46 | + int cur = Math.min(pre, maxHeights.get(j)); |
| 47 | + ans += cur; |
| 48 | + pre = cur; |
| 49 | + } |
| 50 | +
|
| 51 | + pre = maxHeights.get(i); |
| 52 | + for (int j = i + 1; j < maxHeights.size(); j++) { |
| 53 | + int cur = Math.min(pre, maxHeights.get(j)); |
| 54 | + ans += cur; |
| 55 | + pre = cur; |
| 56 | + } |
| 57 | + res = Math.max(res, ans); |
| 58 | + } |
| 59 | + return res; |
| 60 | + }*/ |
| 61 | + |
| 62 | + |
| 63 | + //单调栈 |
| 64 | + static public long maximumSumOfHeights(List<Integer> maxHeights) { |
| 65 | + long[] left = help(maxHeights); |
| 66 | + |
| 67 | + List<Integer> reverse = new ArrayList<>(); |
| 68 | + for (int i = maxHeights.size() - 1; i >= 0; i--) { |
| 69 | + reverse.add(maxHeights.get(i)); |
| 70 | + } |
| 71 | + long[] right = help(reverse); |
| 72 | + |
| 73 | + long ans = 0; |
| 74 | + for (int i = 0; i < maxHeights.size(); i++) { |
| 75 | + ans = Math.max(ans, left[i] + right[maxHeights.size() - i]); |
| 76 | + } |
| 77 | + return ans; |
| 78 | + } |
| 79 | + |
| 80 | + static long[] help(List<Integer> maxHeights) { |
| 81 | + long[] left = new long[maxHeights.size() + 1]; |
| 82 | + ArrayDeque<int[]> deque = new ArrayDeque<>(); |
| 83 | + deque.add(new int[]{0, -1}); |
| 84 | + for (int i = 0; i < maxHeights.size(); i++) { |
| 85 | + while (!deque.isEmpty() && deque.peekLast()[0] > maxHeights.get(i)) { |
| 86 | + deque.pollLast(); |
| 87 | + } |
| 88 | + int minIndex = deque.peekLast()[1]; |
| 89 | + left[i + 1] = left[minIndex + 1] + (i - minIndex) * (long) maxHeights.get(i); |
| 90 | + deque.add(new int[]{maxHeights.get(i), i}); |
| 91 | + } |
| 92 | + return left; |
| 93 | + } |
| 94 | + |
| 95 | + |
| 96 | + public static List<Integer> getPrimes(int n) { |
| 97 | + boolean[] isComposite = new boolean[n + 1]; |
| 98 | + List<Integer> primes = new ArrayList<>(); |
| 99 | + |
| 100 | + for (int i = 2; i <= n; i++) { |
| 101 | + if (!isComposite[i]) { |
| 102 | + primes.add(i); |
| 103 | + for (int j = i * 2; j >= 0 && j <= n; j += i) { // 标记该数的倍数为合数 |
| 104 | + isComposite[j] = true; |
| 105 | + } |
| 106 | + } |
| 107 | + } |
| 108 | + return primes; |
| 109 | + } |
| 110 | + |
| 111 | + static Set<Integer> set = new HashSet<>(); |
| 112 | + |
| 113 | + static { |
| 114 | + |
| 115 | + for (Integer prime : getPrimes(1000001)) { |
| 116 | + set.add(prime); |
| 117 | + } |
| 118 | + } |
| 119 | + |
| 120 | + //负责dfs |
| 121 | + public long countPaths(int n, int[][] edges) { |
| 122 | + Map<Integer, List<Integer>> map = new HashMap<>(); |
| 123 | + for (int[] edge : edges) { |
| 124 | + if (!map.containsKey(edge[0])) { |
| 125 | + map.put(edge[0], new ArrayList<>()); |
| 126 | + } |
| 127 | + if (!map.containsKey(edge[1])) { |
| 128 | + map.put(edge[1], new ArrayList<>()); |
| 129 | + } |
| 130 | + map.get(edge[0]).add(edge[1]); |
| 131 | + map.get(edge[1]).add(edge[0]); |
| 132 | + } |
| 133 | + dfs(1, -1, map); |
| 134 | + return ans; |
| 135 | + } |
| 136 | + |
| 137 | + long ans = 0; |
| 138 | + |
| 139 | + long[] dfs(int cur, int parent, Map<Integer, List<Integer>> map) { |
| 140 | + |
| 141 | + boolean isPrime = set.contains(cur); |
| 142 | + long[] counts = new long[2]; |
| 143 | + |
| 144 | + if (!isPrime) { |
| 145 | + counts[0] = 1; |
| 146 | + } else { |
| 147 | + counts[1] = 1; |
| 148 | + } |
| 149 | + |
| 150 | + for (Integer child : map.getOrDefault(cur, new ArrayList<>())) { |
| 151 | + if (child == parent) continue; |
| 152 | + long[] ints = dfs(child, cur, map); |
| 153 | + ans+=ints[0]*counts[1]+ints[1]*counts[0]; |
| 154 | + if (!isPrime) { |
| 155 | + counts[0]+=ints[0]; |
| 156 | + counts[1]+=ints[1]; |
| 157 | + } else { |
| 158 | + counts[1]+=ints[0]; |
| 159 | + } |
| 160 | + } |
| 161 | + return counts; |
| 162 | + } |
| 163 | + |
| 164 | + public static void main(String[] args) { |
| 165 | + wk364 w = new wk364(); |
| 166 | + w.countPaths(5, new int[][]{ |
| 167 | + {1, 2}, {1, 3}, {2, 4}, {2, 5} |
| 168 | + }); |
| 169 | + } |
| 170 | +} |
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