【DP】 HDOJ 3076 ssworld VS DDD

简单DP。。注意到一个人的血量为0，他就挂了，不能再推到其他情况了。。。输入的是反的。。。

#include <iostream>  #include <queue>  #include <stack>  #include <map>  #include <set>  #include <bitset>  #include <cstdio>  #include <algorithm>  #include <cstring>  #include <climits>  #include <cstdlib>#include <cmath>#include <time.h>#define maxn 2005#define maxm 150000#define eps 1e-10#define mod 1000000007#define INF 999999999#define lowbit(x) (x&(-x))#define mp mark_pair#define ls o<<1#define rs o<<1 | 1#define lson o<<1, L, mid  #define rson o<<1 | 1, mid+1, R  //typedef vector<int>::iterator IT;typedef long long LL;//typedef int LL;using namespace std;LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}// headdouble dp[maxn][maxn];double t1[maxn], t2[maxn];double a, b, c;int n, m;void read(void){for(int i = 1; i <= 6; i++) scanf("%lf", &t1[i]);for(int i = 1; i <= 6; i++) scanf("%lf", &t2[i]);}void work(void){a = b = c = 0;for(int i = 1; i <= 6; i++)for(int j = 1; j <= 6; j++) {if(i == j) c += t1[i] * t2[j];if(i < j) a += t1[i] * t2[j];if(i > j) b += t1[i] * t2[j];}for(int i = 0; i <= n+1; i++)for(int j = 0; j <= m+1; j++)dp[i][j] = 0;dp[n][m] = 1;if(fabs(1 - c) < eps) {printf("0.000000\n");return;}double t = 1 - c;for(int i = n; i >= 0; i--)for(int j = m; j >= 0; j--) {if(i == n && j == m) continue;if(i && j ) dp[i][j] = (a * dp[i+1][j] + b * dp[i][j+1]) / t;else if(i) dp[i][j] = (b * dp[i][j+1]) / t;else if(j) dp[i][j] = (a * dp[i+1][j]) / t;else dp[i][j] = 0;}double ans = 0;for(int i = 1; i <= n; i++) ans += dp[i][0];printf("%.6f\n", ans);}int main(void){while(scanf("%d%d", &m, &n)!=EOF) {read();work();}return 0;}