|
| 1 | +package weekly; |
| 2 | + |
| 3 | +import java.util.ArrayList; |
| 4 | +import java.util.Arrays; |
| 5 | +import java.util.Collections; |
| 6 | +import java.util.HashMap; |
| 7 | +import java.util.List; |
| 8 | +import java.util.Map; |
| 9 | + |
| 10 | +public class wk368 { |
| 11 | + /* public int minimumSum(int[] nums) { |
| 12 | + int ans = Integer.MAX_VALUE; |
| 13 | + for (int i = 0; i < nums.length; i++) { |
| 14 | + for (int j = i + 1; j < nums.length; j++) { |
| 15 | + for (int k = j + 1; k < nums.length; k++) { |
| 16 | + if (nums[i] < nums[j] && nums[j] > nums[k]) { |
| 17 | + ans = Math.min(nums[i] + nums[j] + nums[k], ans); |
| 18 | + } |
| 19 | + } |
| 20 | + } |
| 21 | + } |
| 22 | + return ans == Integer.MAX_VALUE ? -1 : ans; |
| 23 | + }*/ |
| 24 | + |
| 25 | + |
| 26 | + //前后缀 |
| 27 | + public int minimumSum(int[] nums) { |
| 28 | + int[] minLeft = new int[nums.length + 1]; |
| 29 | + int[] minRight = new int[nums.length + 1]; |
| 30 | + |
| 31 | + minLeft[0] = (int) 1e9 + 7; |
| 32 | + minRight[nums.length] = (int) 1e9 + 7; |
| 33 | + for (int i = 0; i < nums.length; i++) { |
| 34 | + minLeft[i + 1] = Math.min(nums[i], minLeft[i]); |
| 35 | + } |
| 36 | + |
| 37 | + for (int i = nums.length - 1; i >= 0; i--) { |
| 38 | + minRight[i] = Math.min(nums[i], minRight[i + 1]); |
| 39 | + } |
| 40 | + |
| 41 | + int ans = Integer.MAX_VALUE; |
| 42 | + for (int i = 1; i < nums.length - 1; i++) { |
| 43 | + if (minLeft[i] < nums[i] && minRight[i + 1] < nums[i]) { |
| 44 | + ans = Math.min(ans, minLeft[i] + nums[i] + minRight[i + 1]); |
| 45 | + } |
| 46 | + } |
| 47 | + |
| 48 | + return ans == Integer.MAX_VALUE ? -1 : ans; |
| 49 | + } |
| 50 | + |
| 51 | + |
| 52 | + //找出最小分组 |
| 53 | + static public int minGroupsForValidAssignment(int[] nums) { |
| 54 | + Map<Integer, List<Integer>> map = new HashMap<>(); |
| 55 | + for (int i = 0; i < nums.length; i++) { |
| 56 | + if (!map.containsKey(nums[i])) map.put(nums[i], new ArrayList<>()); |
| 57 | + map.get(nums[i]).add(i); |
| 58 | + } |
| 59 | + |
| 60 | + List<Integer> count = new ArrayList<>(); |
| 61 | + int min = Integer.MAX_VALUE; |
| 62 | + for (Map.Entry<Integer, List<Integer>> entry : map.entrySet()) { |
| 63 | + count.add(entry.getValue().size()); |
| 64 | + min = Math.min(min, entry.getValue().size()); |
| 65 | + } |
| 66 | + int ans = nums.length; |
| 67 | + |
| 68 | + for (int i = 1; i <= min; i++) { |
| 69 | + ans = Math.min(ans, check(i, count)); |
| 70 | + } |
| 71 | + |
| 72 | + return ans; |
| 73 | + } |
| 74 | + |
| 75 | + static int check(int min, List<Integer> count) { |
| 76 | + int ans = 0; |
| 77 | + for (Integer c : count) { |
| 78 | + if (c / min < c % min) { |
| 79 | + return Integer.MAX_VALUE; |
| 80 | + } |
| 81 | + // |
| 82 | + ans += (c + min) / (min + 1); |
| 83 | + } |
| 84 | + return ans; |
| 85 | + } |
| 86 | + |
| 87 | + |
| 88 | + //预处理+记忆化搜索好写一点 |
| 89 | + public int minimumChanges(String s, int k) { |
| 90 | + int n = s.length(); |
| 91 | + int[][] modify = new int[n - 1][n]; |
| 92 | + for (int left = 0; left < n - 1; left++) { |
| 93 | + for (int right = left + 1; right < n; right++) { |
| 94 | + modify[left][right] = getModify(s.substring(left, right + 1)); |
| 95 | + } |
| 96 | + } |
| 97 | + |
| 98 | + int[][] memo = new int[k][n]; |
| 99 | + for (int i = 0; i < k; i++) { |
| 100 | + Arrays.fill(memo[i], -1); // -1 表示没有计算过 |
| 101 | + } |
| 102 | + return dfs(k - 1, n - 1, memo, modify); |
| 103 | + } |
| 104 | + |
| 105 | + private static final int MX = 201; |
| 106 | + private static final List<Integer>[] divisors = new ArrayList[MX]; |
| 107 | + |
| 108 | + static { |
| 109 | + // 预处理每个数的真因子，时间复杂度 O(MX*logMX) |
| 110 | + Arrays.setAll(divisors, k -> new ArrayList<>()); |
| 111 | + for (int i = 1; i < MX; i++) { |
| 112 | + for (int j = i * 2; j < MX; j += i) { |
| 113 | + divisors[j].add(i); |
| 114 | + } |
| 115 | + } |
| 116 | + } |
| 117 | + |
| 118 | + private int getModify(String S) { |
| 119 | + char[] s = S.toCharArray(); |
| 120 | + int n = s.length; |
| 121 | + int res = n; |
| 122 | + for (int d : divisors[n]) { |
| 123 | + int cnt = 0; |
| 124 | + for (int i0 = 0; i0 < d; i0++) { |
| 125 | + for (int i = i0, j = n - d + i0; i < j; i += d, j -= d) { |
| 126 | + if (s[i] != s[j]) { |
| 127 | + cnt++; |
| 128 | + } |
| 129 | + } |
| 130 | + } |
| 131 | + res = Math.min(res, cnt); |
| 132 | + } |
| 133 | + return res; |
| 134 | + } |
| 135 | + |
| 136 | + private int dfs(int i, int j, int[][] memo, int[][] modify) { |
| 137 | + if (i == 0) { // 递归边界 |
| 138 | + return modify[0][j]; |
| 139 | + } |
| 140 | + if (memo[i][j] != -1) { // 之前计算过 |
| 141 | + return memo[i][j]; |
| 142 | + } |
| 143 | + int res = Integer.MAX_VALUE; |
| 144 | + for (int L = i * 2; L < j; L++) { |
| 145 | + res = Math.min(res, dfs(i - 1, L - 1, memo, modify) + modify[L][j]); |
| 146 | + } |
| 147 | + return memo[i][j] = res; // 记忆化 |
| 148 | + } |
| 149 | + |
| 150 | + |
| 151 | + public static void main(String[] args) { |
| 152 | + minGroupsForValidAssignment(new int[]{ |
| 153 | + 1, 3, 2, 1, 1, 3, 1, 2, 1, 1, 1, 1, 1, 3, 1}); |
| 154 | + } |
| 155 | +} |
0 commit comments