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51 lines
1.2 KiB
51 lines
1.2 KiB
package 第01期.mca_test;
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public class Problem_0213_HouseRobberII {
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// arr 长度大于等于1
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public static int pickMaxSum(int[] arr) {
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int n = arr.length;
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// dp[i] : arr[0..i]范围上，随意选择，但是，任何两数不能相邻。得到的最大累加和是多少？
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int[] dp = new int[n];
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dp[0] = arr[0];
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dp[1] = Math.max(arr[0], arr[1]);
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for (int i = 2; i < n; i++) {
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int p1 = arr[i];
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int p2 = dp[i - 1];
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int p3 = arr[i] + dp[i - 2];
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dp[i] = Math.max(p1, Math.max(p2, p3));
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}
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return dp[n - 1];
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}
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public static int rob(int[] nums) {
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if (nums == null || nums.length == 0) {
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return 0;
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}
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if (nums.length == 1) {
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return nums[0];
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}
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if (nums.length == 2) {
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return Math.max(nums[0], nums[1]);
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}
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int pre2 = nums[0];
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int pre1 = Math.max(nums[0], nums[1]);
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for (int i = 2; i < nums.length - 1; i++) {
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int tmp = Math.max(pre1, nums[i] + pre2);
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pre2 = pre1;
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pre1 = tmp;
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}
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int ans1 = pre1;
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pre2 = nums[1];
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pre1 = Math.max(nums[1], nums[2]);
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for (int i = 3; i < nums.length; i++) {
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int tmp = Math.max(pre1, nums[i] + pre2);
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pre2 = pre1;
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pre1 = tmp;
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}
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int ans2 = pre1;
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return Math.max(ans1, ans2);
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}
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}
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