From 8f8a26a40ab51c7f4c87c8df1c009f91f2413dae Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E5=B7=A6=E7=A8=8B=E4=BA=91?= Date: Thu, 7 Jan 2021 23:11:50 +0800 Subject: [PATCH] modify code --- src/class20/Code01_PalindromeSubsequence.java | 46 ++++++ src/class20/Code02_HorseJump.java | 92 +++++++++--- src/class20/Code03_Coffee.java | 134 +++++++----------- 3 files changed, 167 insertions(+), 105 deletions(-) diff --git a/src/class20/Code01_PalindromeSubsequence.java b/src/class20/Code01_PalindromeSubsequence.java index 062f242..dd38429 100644 --- a/src/class20/Code01_PalindromeSubsequence.java +++ b/src/class20/Code01_PalindromeSubsequence.java @@ -3,6 +3,52 @@ package class20; // 测试链接：https://leetcode.com/problems/longest-palindromic-subsequence/ public class Code01_PalindromeSubsequence { + public static int lpsl1(String s) { + if (s == null || s.length() == 0) { + return 0; + } + char[] str = s.toCharArray(); + return f(str, 0, str.length - 1); + } + + // str[L..R]最长回文子序列长度返回 + public static int f(char[] str, int L, int R) { + if (L == R) { + return 1; + } + if (L == R - 1) { + return str[L] == str[R] ? 2 : 1; + } + int p1 = f(str, L + 1, R - 1); + int p2 = f(str, L, R - 1); + int p3 = f(str, L + 1, R); + int p4 = str[L] != str[R] ? 0 : (2 + f(str, L + 1, R - 1)); + return Math.max(Math.max(p1, p2), Math.max(p3, p4)); + } + + public static int lpsl2(String s) { + if (s == null || s.length() == 0) { + return 0; + } + char[] str = s.toCharArray(); + int N = str.length; + int[][] dp = new int[N][N]; + dp[N - 1][N - 1] = 1; + for (int i = 0; i < N - 1; i++) { + dp[i][i] = 1; + dp[i][i + 1] = str[i] == str[i + 1] ? 2 : 1; + } + for (int L = N - 3; L >= 0; L--) { + for (int R = L + 2; R < N; R++) { + dp[L][R] = Math.max(dp[L][R - 1], dp[L + 1][R]); + if (str[L] == str[R]) { + dp[L][R] = Math.max(dp[L][R], 2 + dp[L + 1][R - 1]); + } + } + } + return dp[0][N - 1]; + } + public static int longestPalindromeSubseq1(String s) { if (s == null || s.length() == 0) { return 0; diff --git a/src/class20/Code02_HorseJump.java b/src/class20/Code02_HorseJump.java index 4744f1e..f96f4a1 100644 --- a/src/class20/Code02_HorseJump.java +++ b/src/class20/Code02_HorseJump.java @@ -2,6 +2,60 @@ package class20; public class Code02_HorseJump { + // 当前来到的位置是（x,y） + // 还剩下rest步需要跳 + // 跳完rest步，正好跳到a，b的方法数是多少？ + // 10 * 9 + public static int jump(int a, int b, int k) { + return process(0, 0, k, a, b); + } + + public static int process(int x, int y, int rest, int a, int b) { + if (x < 0 || x > 9 || y < 0 || y > 8) { + return 0; + } + if (rest == 0) { + return (x == a && y == b) ? 1 : 0; + } + int ways = process(x + 2, y + 1, rest - 1, a, b); + ways += process(x + 1, y + 2, rest - 1, a, b); + ways += process(x - 1, y + 2, rest - 1, a, b); + ways += process(x - 2, y + 1, rest - 1, a, b); + ways += process(x - 2, y - 1, rest - 1, a, b); + ways += process(x - 1, y - 2, rest - 1, a, b); + ways += process(x + 1, y - 2, rest - 1, a, b); + ways += process(x + 2, y - 1, rest - 1, a, b); + return ways; + } + + public static int dp(int a, int b, int k) { + int[][][] dp = new int[10][9][k + 1]; + dp[a][b][0] = 1; + for (int rest = 1; rest <= k; rest++) { + for (int x = 0; x < 10; x++) { + for (int y = 0; y < 9; y++) { + int ways = pick(dp, x + 2, y + 1, rest - 1); + ways += pick(dp, x + 1, y + 2, rest - 1); + ways += pick(dp, x - 1, y + 2, rest - 1); + ways += pick(dp, x - 2, y + 1, rest - 1); + ways += pick(dp, x - 2, y - 1, rest - 1); + ways += pick(dp, x - 1, y - 2, rest - 1); + ways += pick(dp, x + 1, y - 2, rest - 1); + ways += pick(dp, x + 2, y - 1, rest - 1); + dp[x][y][rest] = ways; + } + } + } + return dp[0][0][k]; + } + + public static int pick(int[][][] dp, int x, int y, int rest) { + if (x < 0 || x > 9 || y < 0 || y > 8) { + return 0; + } + return dp[x][y][rest]; + } + public static int ways(int a, int b, int step) { return f(0, 0, step, a, b); } @@ -13,32 +67,22 @@ public class Code02_HorseJump { if (step == 0) { return (i == a && j == b) ? 1 : 0; } - return f(i - 2, j + 1, step - 1, a, b) - + f(i - 1, j + 2, step - 1, a, b) - + f(i + 1, j + 2, step - 1, a, b) - + f(i + 2, j + 1, step - 1, a, b) - + f(i + 2, j - 1, step - 1, a, b) - + f(i + 1, j - 2, step - 1, a, b) - + f(i - 1, j - 2, step - 1, a, b) - + f(i - 2, j - 1, step - 1, a, b); + return f(i - 2, j + 1, step - 1, a, b) + f(i - 1, j + 2, step - 1, a, b) + f(i + 1, j + 2, step - 1, a, b) + + f(i + 2, j + 1, step - 1, a, b) + f(i + 2, j - 1, step - 1, a, b) + f(i + 1, j - 2, step - 1, a, b) + + f(i - 1, j - 2, step - 1, a, b) + f(i - 2, j - 1, step - 1, a, b); } - - + public static int waysdp(int a, int b, int s) { - int[][][] dp = new int[10][9][s+1]; + int[][][] dp = new int[10][9][s + 1]; dp[a][b][0] = 1; - for(int step = 1 ; step <= s;step++ ) { // 按层来 - for(int i = 0 ; i < 10;i++) { - for(int j = 0 ; j < 9; j++) { - dp[i][j][step] = getValue(dp,i - 2, j + 1, step - 1) - + getValue(dp,i - 1, j + 2, step - 1) - + getValue(dp,i + 1, j + 2, step - 1) - + getValue(dp,i + 2, j + 1, step - 1) - + getValue(dp,i + 2, j - 1, step - 1) - + getValue(dp,i + 1, j - 2, step - 1) - + getValue(dp,i - 1, j - 2, step - 1) - + getValue(dp,i - 2, j - 1, step - 1); + for (int step = 1; step <= s; step++) { // 按层来 + for (int i = 0; i < 10; i++) { + for (int j = 0; j < 9; j++) { + dp[i][j][step] = getValue(dp, i - 2, j + 1, step - 1) + getValue(dp, i - 1, j + 2, step - 1) + + getValue(dp, i + 1, j + 2, step - 1) + getValue(dp, i + 2, j + 1, step - 1) + + getValue(dp, i + 2, j - 1, step - 1) + getValue(dp, i + 1, j - 2, step - 1) + + getValue(dp, i - 1, j - 2, step - 1) + getValue(dp, i - 2, j - 1, step - 1); } } } @@ -58,6 +102,8 @@ public class Code02_HorseJump { int y = 7; int step = 10; System.out.println(ways(x, y, step)); - System.out.println(waysdp(x, y, step)); + System.out.println(dp(x, y, step)); + + System.out.println(jump(x, y, step)); } } diff --git a/src/class20/Code03_Coffee.java b/src/class20/Code03_Coffee.java index 070faa9..970cfe9 100644 --- a/src/class20/Code03_Coffee.java +++ b/src/class20/Code03_Coffee.java @@ -14,14 +14,14 @@ import java.util.PriorityQueue; // 假设时间点从0开始，返回所有人喝完咖啡并洗完咖啡杯的全部过程结束后，至少来到什么时间点。 public class Code03_Coffee { - // 方法一：暴力尝试方法 - public static int minTime1(int[] arr, int n, int a, int b) { + // 验证的方法，彻底的暴力，不要脸的暴力 + public static int right(int[] arr, int n, int a, int b) { int[] times = new int[arr.length]; int[] drink = new int[n]; return forceMake(arr, times, 0, drink, n, a, b); } - // 方法一，每个人暴力尝试用每一个咖啡机给自己做咖啡 + // 每个人暴力尝试用每一个咖啡机给自己做咖啡 public static int forceMake(int[] arr, int[] times, int kth, int[] drink, int n, int a, int b) { if (kth == n) { int[] drinkSorted = Arrays.copyOf(drink, kth); @@ -41,7 +41,6 @@ public class Code03_Coffee { return time; } - // 方法一，暴力尝试洗咖啡杯的方式 public static int forceWash(int[] drinks, int a, int b, int index, int washLine, int time) { if (index == drinks.length) { return time; @@ -56,7 +55,7 @@ public class Code03_Coffee { return Math.min(ans1, ans2); } - // 方法二：稍微好一点的解法 + // 以下为贪心+优良暴力 public static class Machine { public int timePoint; public int workTime; @@ -76,8 +75,8 @@ public class Code03_Coffee { } - // 方法二，每个人暴力尝试用每一个咖啡机给自己做咖啡，优化成贪心 - public static int minTime2(int[] arr, int n, int a, int b) { + // 优良一点的暴力尝试的方法 + public static int minTime1(int[] arr, int n, int a, int b) { PriorityQueue heap = new PriorityQueue(new MachineComparator()); for (int i = 0; i < arr.length; i++) { heap.add(new Machine(0, arr[i])); @@ -89,66 +88,32 @@ public class Code03_Coffee { drinks[i] = cur.timePoint; heap.add(cur); } - return process(drinks, a, b, 0, 0); + return bestTime(drinks, a, b, 0, 0); } - // 方法二，洗咖啡杯的方式和原来一样，只是这个暴力版本减少了一个可变参数 - - // process(drinks, 3, 10, 0,0) - // a 洗一杯的时间 固定变量 - // b 自己挥发干净的时间 固定变量 - // drinks 每一个员工喝完的时间 固定变量 - // drinks[0..index-1]都已经干净了，不用你操心了 - // drinks[index...]都想变干净，这是我操心的，washLine表示洗的机器何时可用 - // drinks[index...]变干净，最少的时间点返回 - public static int process(int[] drinks, int a, int b, int index, int washLine) { - if (index == drinks.length - 1) { - return Math.min(Math.max(washLine, drinks[index]) + a, drinks[index] + b); + // drinks 所有杯子可以开始洗的时间 + // wash 单杯洗干净的时间（串行） + // air 挥发干净的时间(并行) + // free 洗的机器什么时候可用 + // drinks[index.....]都变干净，最早的结束时间（返回） + public static int bestTime(int[] drinks, int wash, int air, int index, int free) { + if (index == drinks.length) { + return 0; } - // 剩不止一杯咖啡 - // wash是我当前的咖啡杯，洗完的时间 - int wash = Math.max(washLine, drinks[index]) + a;// 洗，index一杯，结束的时间点 - // index+1...变干净的最早时间 - int next1 = process(drinks, a, b, index + 1, wash); - // index.... - int p1 = Math.max(wash, next1); - int dry = drinks[index] + b; // 挥发，index一杯，结束的时间点 - int next2 = process(drinks, a, b, index + 1, washLine); - int p2 = Math.max(dry, next2); - return Math.min(p1, p2); - } + // index号杯子 决定洗 + int selfClean1 = Math.max(drinks[index], free) + wash; + int restClean1 = bestTime(drinks, wash, air, index + 1, selfClean1); + int p1 = Math.max(selfClean1, restClean1); - public static int dp(int[] drinks, int a, int b) { - if (a >= b) { - return drinks[drinks.length - 1] + b; - } - // a < b - int N = drinks.length; - int limit = 0; // 咖啡机什么时候可用 - for (int i = 0; i < N; i++) { - limit = Math.max(limit, drinks[i]) + a; - } - int[][] dp = new int[N][limit + 1]; - // N-1行，所有的值 - for (int washLine = 0; washLine <= limit; washLine++) { - dp[N - 1][washLine] = Math.min(Math.max(washLine, drinks[N - 1]) + a, drinks[N - 1] + b); - } - for (int index = N - 2; index >= 0; index--) { - for (int washLine = 0; washLine <= limit; washLine++) { - int p1 = Integer.MAX_VALUE; - int wash = Math.max(washLine, drinks[index]) + a; - if (wash <= limit) { - p1 = Math.max(wash, dp[index + 1][wash]); - } - int p2 = Math.max(drinks[index] + b, dp[index + 1][washLine]); - dp[index][washLine] = Math.min(p1, p2); - } - } - return dp[0][0]; + // index号杯子 决定挥发 + int selfClean2 = drinks[index] + air; + int restClean2 = bestTime(drinks, wash, air, index + 1, free); + int p2 = Math.max(selfClean2, restClean2); + return Math.min(p1, p2); } - // 方法三：最终版本，把方法二洗咖啡杯的暴力尝试进一步优化成动态规划 - public static int minTime3(int[] arr, int n, int a, int b) { + // 方法二，贪心+优良尝试改成动态规划 + public static int minTime2(int[] arr, int n, int a, int b) { PriorityQueue heap = new PriorityQueue(new MachineComparator()); for (int i = 0; i < arr.length; i++) { heap.add(new Machine(0, arr[i])); @@ -160,18 +125,29 @@ public class Code03_Coffee { drinks[i] = cur.timePoint; heap.add(cur); } - if (a >= b) { - return drinks[n - 1] + b; - } - int[][] dp = new int[n][drinks[n - 1] + n * a]; - for (int i = 0; i < dp[0].length; i++) { - dp[n - 1][i] = Math.min(Math.max(i, drinks[n - 1]) + a, drinks[n - 1] + b); - } - for (int row = n - 2; row >= 0; row--) { // row 咖啡杯的编号 - int washLine = drinks[row] + (row + 1) * a; - for (int col = 0; col < washLine; col++) { - int wash = Math.max(col, drinks[row]) + a; - dp[row][col] = Math.min(Math.max(wash, dp[row + 1][wash]), Math.max(drinks[row] + b, dp[row + 1][col])); + return bestTimeDp(drinks, a, b); + } + + public static int bestTimeDp(int[] drinks, int wash, int air) { + int N = drinks.length; + int maxFree = 0; + for (int i = 0; i < drinks.length; i++) { + maxFree = Math.max(maxFree, drinks[i]) + wash; + } + int[][] dp = new int[N + 1][maxFree + 1]; + for (int index = N - 1; index >= 0; index--) { + for (int free = 0; free <= maxFree; free++) { + int selfClean1 = Math.max(drinks[index], free) + wash; + if (selfClean1 > maxFree) { + break; // 因为free后面的也都不用填了 + } + int restClean1 = dp[index + 1][selfClean1]; + int p1 = Math.max(selfClean1, restClean1); + // index号杯子 决定挥发 + int selfClean2 = drinks[index] + air; + int restClean2 = dp[index + 1][free]; + int p2 = Math.max(selfClean2, restClean2); + dp[index][free] = Math.min(p1, p2); } } return dp[0][0]; @@ -196,12 +172,6 @@ public class Code03_Coffee { } public static void main(String[] args) { - int[] test = { 1, 1, 5, 5, 7, 10, 12, 12, 12, 12, 12, 12, 15 }; - int a1 = 3; - int b1 = 10; - System.out.println(process(test, a1, b1, 0, 0)); - System.out.println(dp(test, a1, b1)); - int len = 5; int max = 9; int testTime = 50000; @@ -210,9 +180,9 @@ public class Code03_Coffee { int n = (int) (Math.random() * 5) + 1; int a = (int) (Math.random() * 5) + 1; int b = (int) (Math.random() * 10) + 1; - int ans1 = minTime1(arr, n, a, b); - int ans2 = minTime2(arr, n, a, b); - int ans3 = minTime3(arr, n, a, b); + int ans1 = right(arr, n, a, b); + int ans2 = minTime1(arr, n, a, b); + int ans3 = minTime2(arr, n, a, b); if (ans1 != ans2 || ans2 != ans3) { printArray(arr); System.out.println("n : " + n);