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101 lines
2.4 KiB
101 lines
2.4 KiB
package class22;
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public class Code01_KillMonster {
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public static double right(int N, int M, int K) {
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if (N < 1 || M < 1 || K < 1) {
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return 0;
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}
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long all = (long) Math.pow(M + 1, K);
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long kill = process(K, M, N);
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return (double) ((double) kill / (double) all);
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}
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// 怪兽还剩hp点血
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// 每次的伤害在[0~M]范围上
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// 还有times次可以砍
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// 返回砍死的情况数！
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public static long process(int times, int M, int hp) {
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if (times == 0) {
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return hp <= 0 ? 1 : 0;
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}
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if (hp <= 0) {
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return (long) Math.pow(M + 1, times);
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}
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long ways = 0;
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for (int i = 0; i <= M; i++) {
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ways += process(times - 1, M, hp - i);
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}
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return ways;
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}
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public static double dp1(int N, int M, int K) {
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if (N < 1 || M < 1 || K < 1) {
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return 0;
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}
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long all = (long) Math.pow(M + 1, K);
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long[][] dp = new long[K + 1][N + 1];
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dp[0][0] = 1;
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for (int times = 1; times <= K; times++) {
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dp[times][0] = (long) Math.pow(M + 1, times);
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for (int hp = 1; hp <= N; hp++) {
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long ways = 0;
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for (int i = 0; i <= M; i++) {
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if (hp - i >= 0) {
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ways += dp[times - 1][hp - i];
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} else {
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ways += (long) Math.pow(M + 1, times - 1);
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}
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}
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dp[times][hp] = ways;
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}
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}
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long kill = dp[K][N];
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return (double) ((double) kill / (double) all);
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}
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public static double dp2(int N, int M, int K) {
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if (N < 1 || M < 1 || K < 1) {
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return 0;
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}
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long all = (long) Math.pow(M + 1, K);
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long[][] dp = new long[K + 1][N + 1];
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dp[0][0] = 1;
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for (int times = 1; times <= K; times++) {
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dp[times][0] = (long) Math.pow(M + 1, times);
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for (int hp = 1; hp <= N; hp++) {
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dp[times][hp] = dp[times][hp - 1] + dp[times - 1][hp];
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if (hp - 1 - M >= 0) {
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dp[times][hp] -= dp[times - 1][hp - 1 - M];
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} else {
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dp[times][hp] -= Math.pow(M + 1, times - 1);
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}
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}
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}
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long kill = dp[K][N];
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return (double) ((double) kill / (double) all);
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}
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public static void main(String[] args) {
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int NMax = 10;
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int MMax = 10;
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int KMax = 10;
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int testTime = 200;
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System.out.println("测试开始");
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for (int i = 0; i < testTime; i++) {
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int N = (int) (Math.random() * NMax);
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int M = (int) (Math.random() * MMax);
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int K = (int) (Math.random() * KMax);
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double ans1 = right(N, M, K);
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double ans2 = dp1(N, M, K);
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double ans3 = dp2(N, M, K);
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if (ans1 != ans2 || ans1 != ans3) {
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System.out.println("Oops!");
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break;
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}
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}
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System.out.println("测试结束");
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}
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}
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