【DP】 codeforces 464C Substitutes in Number

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倒过来DP即可。。。

#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 100005#define maxm 400005#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);}// headLL delta[20], shift[20];string s, q[maxn];int main(void){int n;cin >> s;scanf("%d", &n);for(int i = 0; i <= 10; i++) delta[i] = i, shift[i] = 10;for(int i = 1; i <= n; i++) cin >> q[i];for(int i = n; i >= 1; i--) {int len = q[i].size();LL t = 0, tt = 1;for(int j = len-1; j >= 3; j--) {t = (t + delta[q[i][j] - '0'] * tt) % mod;tt = shift[q[i][j] - '0'] * tt % mod;}int x = q[i][0] - '0';delta[x] = t;shift[x] = tt;}int len = s.size();LL ans = 0;for(int i = 0; i < len; i++) ans = (ans * shift[s[i] - '0'] + delta[s[i] - '0']) % mod;printf("%I64d\n", ans);return 0;}

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