modify code

Author: algorithmzuo

src/class47/Code02_RestoreWays.java

@@ -90,10 +90,6 @@ public static int process1(int[] arr, int i, int v, int s) {
 public static int ways2(int[] arr) {
 int N = arr.length;
 int[][][] dp = new int[N][201][3];
-// dp[0][...][...]
-// dp[0][...][2] = 0
-// dp[0][...][0] = 1
-// dp[0][...][1] = 1
 if (arr[0] != 0) {
 dp[0][arr[0]][0] = 1;
 dp[0][arr[0]][1] = 1;
@@ -108,14 +104,14 @@ public static int ways2(int[] arr) {
 for (int s = 0; s < 3; s++) {
 if (arr[i] == 0 || v == arr[i]) {
 if (s == 0 || s == 1) {
-for (int pre = 1; pre < 201; pre++) {
-dp[i][v][s] += dp[i - 1][pre][pre < v ? 0 : (pre == v ? 1 : 2)];
-}
-} else {
-for (int pre = v; pre < 201; pre++) {
-dp[i][v][s] += dp[i - 1][pre][pre < v ? 0 : (pre == v ? 1 : 2)];
+for (int pre = 1; pre < v; pre++) {
+dp[i][v][s] += dp[i - 1][pre][0];
 }
 }
+dp[i][v][s] += dp[i - 1][v][1];
+for (int pre = v + 1; pre < 201; pre++) {
+dp[i][v][s] += dp[i - 1][pre][2];
+}
 }
 }
 }
@@ -143,11 +139,7 @@ public static int ways3(int[] arr) {
 dp[0][v][1] = 1;
 }
 }
-// presum[0~V][0] -> sum0[]
-// presum[0~V][1] -> sum1[]
-// presum[0~V][2] -> sum2[]
 int[][] presum = new int[201][3];
-// presum -> dp[0][..][..] 三张表
 for (int v = 1; v < 201; v++) {
 for (int s = 0; s < 3; s++) {
 presum[v][s] = presum[v - 1][s] + dp[0][v][s];
@@ -158,14 +150,10 @@ public static int ways3(int[] arr) {
 for (int s = 0; s < 3; s++) {
 if (arr[i] == 0 || v == arr[i]) {
 if (s == 0 || s == 1) {
-// dp[i][..][..] -> dp[i-1][..][..]
 dp[i][v][s] += sum(1, v - 1, 0, presum);
-dp[i][v][s] += dp[i - 1][v][1];
-dp[i][v][s] += sum(v + 1, 200, 2, presum);
-} else {
-dp[i][v][s] += dp[i - 1][v][1];
-dp[i][v][s] += sum(v + 1, 200, 2, presum);
 }
+dp[i][v][s] += dp[i - 1][v][1];
+dp[i][v][s] += sum(v + 1, 200, 2, presum);
 }
 }
 }
@@ -188,7 +176,7 @@ public static int sum(int begin, int end, int relation, int[][] presum) {
 
 // for test
 public static int[] generateRandomArray(int len) {
-int[] ans = new int[(int) (Math.random() * len) + 2];
+int[] ans = new int[len];
 for (int i = 0; i < ans.length; i++) {
 if (Math.random() < 0.5) {
 ans[i] = 0;
@@ -209,11 +197,12 @@ public static void printArray(int[] arr) {
 }
 
 public static void main(String[] args) {
-int len = 3;
-int testTime = 10;
-System.out.println("test begin");
+int len = 4;
+int testTime = 15;
+System.out.println("功能测试开始");
 for (int i = 0; i < testTime; i++) {
-int[] arr = generateRandomArray(len);
+int N = (int) (Math.random() * len) + 2;
+int[] arr = generateRandomArray(N);
 int ans0 = ways0(arr);
 int ans1 = ways1(arr);
 int ans2 = ways2(arr);
@@ -222,14 +211,14 @@ public static void main(String[] args) {
 System.out.println("Oops!");
 }
 }
-System.out.println("test finish");
-int[] arr = generateRandomArray(100000);
-System.out.println(arr.length);
+System.out.println("功能测试结束");
+System.out.println("===========");
+int N = 100000;
+int[] arr = generateRandomArray(N);
 long begin = System.currentTimeMillis();
 ways3(arr);
 long end = System.currentTimeMillis();
 System.out.println("run time : " + (end - begin) + " ms");
-
 }
 
 }