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Code01_KillMonster.java
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100 lines (93 loc) · 2.42 KB
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package class22;
public class Code01_KillMonster {
public static double right(int N, int M, int K) {
if (N < 1 || M < 1 || K < 1) {
return 0;
}
long all = (long) Math.pow(M + 1, K);
long kill = process(K, M, N);
return (double) ((double) kill / (double) all);
}
// 怪兽还剩hp点血
// 每次的伤害在[0~M]范围上
// 还有times次可以砍
// 返回砍死的情况数！
public static long process(int times, int M, int hp) {
if (times == 0) {
return hp <= 0 ? 1 : 0;
}
if (hp <= 0) {
return (long) Math.pow(M + 1, times);
}
long ways = 0;
for (int i = 0; i <= M; i++) {
ways += process(times - 1, M, hp - i);
}
return ways;
}
public static double dp1(int N, int M, int K) {
if (N < 1 || M < 1 || K < 1) {
return 0;
}
long all = (long) Math.pow(M + 1, K);
long[][] dp = new long[K + 1][N + 1];
dp[0][0] = 1;
for (int times = 1; times <= K; times++) {
dp[times][0] = (long) Math.pow(M + 1, times);
for (int hp = 1; hp <= N; hp++) {
long ways = 0;
for (int i = 0; i <= M; i++) {
if (hp - i >= 0) {
ways += dp[times - 1][hp - i];
} else {
ways += (long) Math.pow(M + 1, times - 1);
}
}
dp[times][hp] = ways;
}
}
long kill = dp[K][N];
return (double) ((double) kill / (double) all);
}
public static double dp2(int N, int M, int K) {
if (N < 1 || M < 1 || K < 1) {
return 0;
}
long all = (long) Math.pow(M + 1, K);
long[][] dp = new long[K + 1][N + 1];
dp[0][0] = 1;
for (int times = 1; times <= K; times++) {
dp[times][0] = (long) Math.pow(M + 1, times);
for (int hp = 1; hp <= N; hp++) {
dp[times][hp] = dp[times][hp - 1] + dp[times - 1][hp];
if (hp - 1 - M >= 0) {
dp[times][hp] -= dp[times - 1][hp - 1 - M];
} else {
dp[times][hp] -= Math.pow(M + 1, times - 1);
}
}
}
long kill = dp[K][N];
return (double) ((double) kill / (double) all);
}
public static void main(String[] args) {
int NMax = 10;
int MMax = 10;
int KMax = 10;
int testTime = 200;
System.out.println("测试开始");
for (int i = 0; i < testTime; i++) {
int N = (int) (Math.random() * NMax);
int M = (int) (Math.random() * MMax);
int K = (int) (Math.random() * KMax);
double ans1 = right(N, M, K);
double ans2 = dp1(N, M, K);
double ans3 = dp2(N, M, K);
if (ans1 != ans2 || ans1 != ans3) {
System.out.println("Oops!");
break;
}
}
System.out.println("测试结束");
}
}