Codeforces 676E The Last Fight Between Human and AI 规律

链接

题意

思路

代码

#include <iostream>
#include <cstdio>
#include <vector>
#include <stack>
#include <queue>
#include <algorithm>
#include <map>
#include <set>
#include <cmath>
#include <cstring>
#include <string>

#define LL long long
#define INF 0x3f3f3f3f
#define eps 1e-8
#define MAXN 100005
using namespace std;

int a[MAXN];
int main(){
#ifndef ONLINE_JUDGE
freopen("in.txt", "r", stdin);
//freopen("out.txt", "w", stdout);
#endif // ONLINE_JUDGE
int n, k;
while(~scanf("%d%d", &n, &k)){
int unk = 0;
for(int i = 0; i <= n; ++i){
char s[20];
scanf("%s", s);
if(s[0] == '?'){
a[i] = INF;
++unk;
}
else{
a[i] = atoi(s);
}
}
if(k == 0){
if(a[0] == 0){
printf("Yes\n");
}
else if(a[0] == INF){
if((n + 1 - unk) & 1){
printf("Yes\n");
}
else{
printf("No\n");
}
}
else{
printf("No\n");
}
}
else{
if(unk > 0){
if((n + 1) & 1){
printf("No\n");
}
else{
printf("Yes\n");
}
}
else{
double res = 0;
for(int i = n; i >= 0; --i){
res = res * k + a[i];

}
if(res == 0){
printf("Yes\n");
}
else{
printf("No\n");
}
}
}
}
}