def solve_NK3(N,K,A): diff = [A[0] for i in range(N)] S = A[0] for i in range(1,N): diff[i] = S - A[i] if diff[i] < 0: return 0 S += A[i] mod = 998244353 memo = {} def dp(i,l,r,s): if (i,l,r,s) in memo: return memo[i,l,r,s] if l>r: return 0 if not i: first = diff[0] - s if l<=first<=r and -K<=first<=K: return 1 else: return 0 res = 0 if diff[i]: L = max((l+s+diff[i]+1)//2,-K+s+diff[i]) R = min((r+s+diff[i])//2,K+s+diff[i]) res += dp(i-1,L,R,0) res %= mod if s%2==diff[i] and (l+1)%2==1 and -K<=r//2<=K: for new_s in range(1,3*K+1): res += dp(i-1,r//2-new_s,r//2-new_s,s//2+diff[i]+new_s) res %= mod if diff[i]<=1 and (l+s-diff[i]+1)//2==(r+s-diff[i])//2: m = -K+s-diff[i]-((l+s-diff[i]+1)//2) M = K+s-diff[i]-((r+s-diff[i])//2) for k in range(max(m,0),min(M,(s-diff[i])//2)+1): res += dp(i-1,(r+s-diff[i])//2-k,(r+s-diff[i])//2-k,diff[i]+k) res %= mod #dp[i-1]のL(S)の範囲 #diff[i]>=2 のとき #-K+diff[i]<=S<=7*K+diff[i] #diff[i]==0,1 のとき #-K+diff[i]<=S<=7*K+diff[i] #-2*K<=S<=K #-K<=S<=7*K #->-2*K<=S<=7*K+1 memo[i,l,r,s] = res return memo[i,l,r,s] return dp(N-1,-N*K,N*K,0) def solve_NK2_cum_WRONG(N,K,A): diff = [A[0] for i in range(N)] S = A[0] for i in range(1,N): diff[i] = S - A[i] if diff[i] < 0: return 0 S += A[i] for i in range(N-1,-1,-1): if diff[i]==0: N = i+1 diff = diff[:i+1] break diff.append(0) mod = 998244353 dp = [[0 for minus in range(6*K+2)] for dp_S in range(10*K)] for dp_S in range(10*K): real_S = diff[1] + dp_S - 2*K - 1 for minus in range(6*K+2): first = diff[0] - minus if first==real_S and -K<=first<=K: dp[dp_S][minus] = 1 cum = [[dp[dp_S][minus] for minus in range(6*K+2)] for dp_S in range(10*K)] for dp_S in range(1,10*K): for minus in range(6*K+2): if minus<6*K+1: cum[dp_S][minus] += cum[dp_S-1][minus+1] for i in range(1,N): ndp = [[0 for minus in range(6*K+2)] for dp_S in range(10*K)] for dp_S in range(10*K): real_S = dp_S + diff[i+1] - 2*K - 1 for minus in range(6*K+2): if diff[i]: L = max((real_S+minus+diff[i]+1)//2,-K+minus+diff[i]) R = min((real_S+minus+diff[i])//2,K+minus+diff[i]) if L==R: pre_dp_S = L - diff[i] + 2*K + 1 if 0<=pre_dp_S<10*K: ndp[dp_S][minus] += dp[pre_dp_S][0] ndp[dp_S][minus] %= mod if minus%2==diff[i] and real_S%2==0 and -K<=real_S//2<=K: pre_dp_S_R = min(10*K-1,real_S//2-1 - diff[i] + 2*K+1) pre_dp_S_L = max(0,real_S//2-3*K - diff[i] + 2*K+1) if pre_dp_S_L<=pre_dp_S_R: ndp[dp_S][minus] += cum[pre_dp_S_R][real_S//2+minus//2+2*K+1-pre_dp_S_R] - cum[pre_dp_S_L][real_S//2+minus//2+2*K+1-pre_dp_S_L] + dp[pre_dp_S_L][real_S//2+minus//2+2*K+1-pre_dp_S_L] ndp[dp_S][minus] %= mod if diff[i]<=1 and (real_S+minus-diff[i])%2==0: m = max(0,-K+minus-diff[i]-(real_S+minus-diff[i])//2) M = min((minus-diff[i])//2,K+minus-diff[i]-(real_S+minus-diff[i])//2) L = min(10*K-1,(real_S+minus-diff[i])//2-diff[i]-m+2*K+1) R = max(0,(real_S+minus-diff[i])//2-diff[i]-M+2*K+1) if L>=R: ndp[dp_S][minus] += cum[L][(real_S+minus-diff[i])//2+2*K+1-L] - cum[R][(real_S+minus-diff[i])//2+2*K+1-R] + dp[R][(real_S+minus-diff[i])//2+2*K+1-R] ndp[dp_S][minus] %= mod ncum = [[ndp[dp_S][minus] for minus in range(6*K+2)] for dp_S in range(10*K)] for dp_S in range(1,10*K): for minus in range(6*K+2): if minus<6*K+1: ncum[dp_S][minus] += ncum[dp_S-1][minus+1] dp,cum = ndp,ncum res = 0 for dp_S in range(1,10*K): res += dp[dp_S][0] res %= mod return res def solve_NK2_memo(N,K,A): diff = [A[0] for i in range(N)] S = A[0] for i in range(1,N): diff[i] = S - A[i] if diff[i] < 0: return 0 S += A[i] diff.append(0) mod = 998244353 memo = {} def dp(i,dp_S,minus): if (i,dp_S,minus) in memo: return memo[i,dp_S,minus] real_S = dp_S + diff[i+1] - 2 * K - 1 if not i: first = diff[0] - minus if first==real_S and -K<=first<=K: memo[i,dp_S,minus] = 1 return 1 else: memo[i,dp_S,minus] = 0 return 0 res = 0 if diff[i]: L = max((real_S+minus+diff[i]+1)//2,-K+minus+diff[i]) R = min((real_S+minus+diff[i])//2,K+minus+diff[i]) if L==R: pre_dp_S = L - diff[i] + 2 * K + 1 res += dp(i-1,pre_dp_S,0) res %= mod if minus%2==diff[i] and real_S%2==0 and -K<=real_S//2<=K: for new_s in range(1,3*K+1): L = max((real_S+1-2*new_s)//2,-K-new_s) R = min((real_S-2*new_s)//2,K-new_s) if L==R: pre_dp_S = L - diff[i] + 2 * K + 1 res += dp(i-1,pre_dp_S,minus//2+diff[i]+new_s) res %= mod if diff[i]<=1: for j in range(minus+1): if (minus-j)%2==diff[i]: L = max((real_S+j+1)//2,-K+j) R = min((real_S+j)//2,K+j) if L==R: pre_dp_S = L - diff[i] + 2 * K + 1 res += dp(i-1,pre_dp_S,(minus-j)//2+diff[i]) res %= mod memo[i,dp_S,minus] = res return res res = 0 for real_S in range(-2*K-1,N*K+1): dp_S = real_S + 2 * K + 1 res += dp(N-1,dp_S,0) res %= mod return res def solve_NK(N,K,A): diff = [A[0] for i in range(N)] S = A[0] for i in range(1,N): diff[i] = S - A[i] if diff[i] < 0: return 0 S += A[i] diff.append(0) dp = [{} for i in range(N-1)] stack = [(N-2,dp_S) for dp_S in range(10*K+10)] while stack: i,j = stack.pop() if j in dp[i]: continue dp[i][j] = [0 for k in range(6*K+2)] if not i: continue if diff[i]: stack.append((i-1,(j+diff[i+1]-2*K-1+diff[i])//2-diff[i]+2*K+1)) if diff[i]<=1: for k in range(-2,1): stack.append((i-1,(j+diff[i+1]-2*K-1+k)//2+2*K+1)) stack.append((i-1,(j+diff[i+1]-2*K-1-diff[i])//2+2*K+1)) cum = [{sum:[0 for minus in range(6*K+2)] for sum in dp[i]} for i in range(N-1)] mod = 998244353 for minus in range(6*K+2): for sum in dp[0]: dp_S = sum - minus real_S = diff[1] + dp_S - 2*K - 1 first = diff[0] - minus if first==real_S and -K<=first<=K: dp[0][sum][minus] = 1 for sum in dp[0]: cum[0][sum][0] = dp[0][sum][0] for minus in range(1,6*K+2): cum[0][sum][minus] = dp[0][sum][minus] + cum[0][sum][minus-1] cum[0][sum][minus] %= mod for i in range(1,N-1): for minus in range(6*K+2): for sum in dp[i]: dp_S = sum - minus real_S = dp_S + diff[i+1] - 2*K - 1 if diff[i]: L = max((real_S+minus+diff[i]+1)//2,-K+minus+diff[i]) R = min((real_S+minus+diff[i])//2,K+minus+diff[i]) if L==R: pre_dp_S = L - diff[i] + 2*K + 1 dp[i][sum][minus] += dp[i-1][pre_dp_S][0] dp[i][sum][minus] %= mod if minus%2==diff[i] and real_S%2==0 and -K<=real_S//2<=K: pre_minus_L = max(0,minus//2+1+diff[i]) pre_minus_R = min(6*K+1,minus//2+3*K+diff[i]) if pre_minus_L<=pre_minus_R: pre_sum = real_S//2+minus//2+2*K+1 dp[i][sum][minus] += cum[i-1][pre_sum][pre_minus_R] - cum[i-1][pre_sum][pre_minus_L] + dp[i-1][pre_sum][pre_minus_L] dp[i][sum][minus] %= mod if diff[i]<=1 and (real_S+minus-diff[i])%2==0: m = max(0,-K+minus-diff[i]-(real_S+minus-diff[i])//2) M = min((minus-diff[i])//2,K+minus-diff[i]-(real_S+minus-diff[i])//2) pre_minus_L = max(0,m+diff[i]) pre_minus_R = min(6*K+1,M+diff[i]) if pre_minus_R>=pre_minus_L: pre_sum = (real_S+minus-diff[i])//2+2*K+1 dp[i][sum][minus] += cum[i-1][pre_sum][pre_minus_R] - cum[i-1][pre_sum][pre_minus_L] + dp[i-1][pre_sum][pre_minus_L] dp[i][sum][minus] %= mod for sum in cum[i]: cum[i][sum][0] = dp[i][sum][0] for minus in range(1,6*K+2): cum[i][sum][minus] = cum[i][sum][minus-1] + dp[i][sum][minus] cum[i][sum][minus] %= mod res = 0 for real_S in range(-N*K,N*K+1): minus = 0 i = N - 1 if diff[i]: L = max((real_S+minus+diff[i]+1)//2,-K+minus+diff[i]) R = min((real_S+minus+diff[i])//2,K+minus+diff[i]) if L==R: pre_dp_S = L - diff[i] + 2*K + 1 res += dp[i-1][pre_dp_S][0] res %= mod if minus%2==diff[i] and real_S%2==0 and -K<=real_S//2<=K: pre_minus_L = max(0,minus//2+1+diff[i]) pre_minus_R = min(6*K+1,minus//2+3*K+diff[i]) if pre_minus_L<=pre_minus_R: pre_sum = real_S//2+minus//2+2*K+1 res += cum[i-1][pre_sum][pre_minus_R] - cum[i-1][pre_sum][pre_minus_L] + dp[i-1][pre_sum][pre_minus_L] res %= mod if diff[i]<=1 and (real_S+minus-diff[i])%2==0: m = max(0,-K+minus-diff[i]-(real_S+minus-diff[i])//2) M = min((minus-diff[i])//2,K+minus-diff[i]-(real_S+minus-diff[i])//2) pre_minus_L = max(0,m+diff[i]) pre_minus_R = min(6*K+1,M+diff[i]) if pre_minus_R>=pre_minus_L: pre_sum = (real_S+minus-diff[i])//2+2*K+1 res += cum[i-1][pre_sum][pre_minus_R] - cum[i-1][pre_sum][pre_minus_L] + dp[i-1][pre_sum][pre_minus_L] res %= mod return res def solve_NK_Constant_Good(N,K,A): diff = [A[0] for i in range(N)] S = A[0] for i in range(1,N): diff[i] = S - A[i] if diff[i] < 0: return 0 S += A[i] diff.append(0) dp = [{} for i in range(N-1)] + [{real_S-diff[N]+2*K+1+0:[0] for real_S in range(-2*K,N*K+1)}] stack = [(N-2,dp_S) for dp_S in range(K-10,3*K+10)] while stack: i,j = stack.pop() if j in dp[i]: continue dp[i][j] = [0 for k in range(4*K+1)] if not i: continue if diff[i]: stack.append((i-1,(j+diff[i+1]-2*K-1+diff[i])//2-diff[i]+2*K+1)) if diff[i]<=1: for k in range(-2,1): stack.append((i-1,(j+diff[i+1]-2*K-1+k)//2+2*K+1)) stack.append((i-1,(j+diff[i+1]-2*K-1-diff[i])//2+2*K+1)) mod = 998244353 for minus in range(4*K+1): for sum in dp[0]: dp_S = sum - minus real_S = diff[1] + dp_S - 2*K - 1 first = diff[0] - minus if first==real_S and -K<=first<=K: dp[0][sum][minus] = 1 if minus: dp[0][sum][minus] += dp[0][sum][minus-1] dp[0][sum][minus] %= mod for i in range(1,N): for sum in dp[i]: for minus in range(len(dp[i][sum])): dp_S = sum - minus real_S = dp_S + diff[i+1] - 2*K - 1 if diff[i]: L = max((real_S+minus+diff[i]+1)//2,-K+minus+diff[i]) R = min((real_S+minus+diff[i])//2,K+minus+diff[i]) if L==R: pre_dp_S = L - diff[i] + 2*K + 1 dp[i][sum][minus] += dp[i-1][pre_dp_S][0] dp[i][sum][minus] %= mod if minus%2==diff[i] and real_S%2==0 and -K<=real_S//2<=K: pre_minus_L = max(0,minus//2+1+diff[i]) pre_minus_R = min(4*K,minus//2+3*K+diff[i]) if pre_minus_L<=pre_minus_R: pre_sum = real_S//2+minus//2+2*K+1 dp[i][sum][minus] += dp[i-1][pre_sum][pre_minus_R] - dp[i-1][pre_sum][pre_minus_L-1] * (pre_minus_L>0) dp[i][sum][minus] %= mod if diff[i]<=1 and (real_S+minus-diff[i])%2==0: m = max(0,-K+minus-diff[i]-(real_S+minus-diff[i])//2) M = min((minus-diff[i])//2,K+minus-diff[i]-(real_S+minus-diff[i])//2) pre_minus_L = max(0,m+diff[i]) pre_minus_R = min(4*K,M+diff[i]) if pre_minus_R>=pre_minus_L: pre_sum = (real_S+minus-diff[i])//2+2*K+1 dp[i][sum][minus] += dp[i-1][pre_sum][pre_minus_R] - dp[i-1][pre_sum][pre_minus_L-1] * (pre_minus_L>0) dp[i][sum][minus] %= mod if minus: dp[i][sum][minus] += dp[i][sum][minus-1] dp[i][sum][minus] %= mod res = 0 for dp_S in dp[N-1]: res += dp[N-1][dp_S][0] res %= mod return res def solve_NK_memory(N,K,A): diff = [A[0] for i in range(N)] S = A[0] for i in range(1,N): diff[i] = S - A[i] if diff[i] < 0: return 0 S += A[i] diff.append(0) dp_sum_set = [set() for i in range(N-1)] + [set([real_S-diff[N]+2*K+1+0 for real_S in range(-2*K,N*K+1)])] stack = [(N-2,dp_S) for dp_S in range(K-10,3*K+10)] while stack: i,j = stack.pop() if j in dp_sum_set[i]: continue dp_sum_set[i].add(j) if not i: continue if diff[i]: stack.append((i-1,(j+diff[i+1]-2*K-1+diff[i])//2-diff[i]+2*K+1)) if diff[i]<=1: for k in range(-2,1): stack.append((i-1,(j+diff[i+1]-2*K-1+k)//2+2*K+1)) stack.append((i-1,(j+diff[i+1]-2*K-1-diff[i])//2+2*K+1)) mod = 998244353 dp = {sum:[0 for i in range(3*K+1)] for sum in dp_sum_set[0]} for minus in range(3*K+1): for sum in dp: dp_S = sum - minus real_S = diff[1] + dp_S - 2*K - 1 first = diff[0] - minus if first==real_S and -K<=first<=K: dp[sum][minus] = 1 if minus: dp[sum][minus] += dp[sum][minus-1] dp[sum][minus] %= mod for i in range(1,N): if i!=N-1: next_dp = {sum:[0 for i in range(3*K+1)] for sum in dp_sum_set[i]} else: next_dp = {sum:[0 for i in range(1)] for sum in dp_sum_set[i]} for sum in next_dp: for minus in range(len(next_dp[sum])): dp_S = sum - minus real_S = dp_S + diff[i+1] - 2*K - 1 if diff[i]: L = max((real_S+minus+diff[i]+1)//2,-K+minus+diff[i]) R = min((real_S+minus+diff[i])//2,K+minus+diff[i]) if L==R: pre_dp_S = L - diff[i] + 2*K + 1 next_dp[sum][minus] += dp[pre_dp_S][0] next_dp[sum][minus] %= mod if minus%2==diff[i] and real_S%2==0 and -K<=real_S//2<=K: pre_minus_L = max(0,minus//2+1+diff[i]) pre_minus_R = min(3*K,minus//2+3*K+diff[i]) if pre_minus_L<=pre_minus_R: pre_sum = real_S//2+minus//2+2*K+1 next_dp[sum][minus] += dp[pre_sum][pre_minus_R] - dp[pre_sum][pre_minus_L-1] * (pre_minus_L>0) next_dp[sum][minus] %= mod if diff[i]<=1 and (real_S+minus-diff[i])%2==0: m = max(0,-K+minus-diff[i]-(real_S+minus-diff[i])//2) M = min((minus-diff[i])//2,K+minus-diff[i]-(real_S+minus-diff[i])//2) pre_minus_L = max(0,m+diff[i]) pre_minus_R = min(3*K,M+diff[i]) if pre_minus_R>=pre_minus_L: pre_sum = (real_S+minus-diff[i])//2+2*K+1 next_dp[sum][minus] += dp[pre_sum][pre_minus_R] - dp[pre_sum][pre_minus_L-1] * (pre_minus_L>0) next_dp[sum][minus] %= mod if minus: next_dp[sum][minus] += next_dp[sum][minus-1] next_dp[sum][minus] %= mod dp = next_dp res = 0 for dp_S in dp: res += dp[dp_S][0] res %= mod return res N,K = map(int,input().split()) A = list(map(int,input().split())) print(solve_NK_memory(N,K,A))