UVA.1262 Password ( dfs求字典序第k大 )

UVA.1262 Password ( dfs求字典序第k大 )

题意分析

代码总览

#include <bits/stdc++.h>
using namespace std;
char pasword1[10][10];
char pasword2[10][10];
bool isoccupy[26];
int num[6];
int t;
int tar;
int temp;
vector<char> v[6];
vector<char> ans;
void dfs(int depth){
if(depth == 5) return;
if(v[depth].size() == 0){
dfs(depth+1);
}else{
for(int i = 0;i<v[depth].size();++i){
if(temp > num[depth]){
temp-=num[depth];
}else{
ans.push_back(v[depth][i]);
dfs(depth+1);
return;
}
}
}
return;
}
int main()
{
//    freopen("in.txt","r",stdin);
scanf("%d",&t);
while(t--){
memset(pasword1,0,sizeof pasword1);
memset(pasword2,0,sizeof pasword2);
for(int i = 0;i<6;++i) v[i].clear();
scanf("%d",&tar);
for(int i = 0;i<6;++i) scanf("%s",pasword1[i]);
for(int i = 0;i<6;++i) scanf("%s",pasword2[i]);
for(int i = 0;i<5;++i){
memset(isoccupy,0,sizeof isoccupy);
for(int j = 0;j<6;++j){
if(isoccupy[pasword1[j][i] - 'A']){
continue;
}
for(int k = 0;k<6;++k){
if(pasword1[j][i] == pasword2[k][i]){
v[i].push_back(pasword1[j][i]);
isoccupy[pasword1[j][i]-'A'] = true;
break;
}
}
}
}
int tot = 1;
bool notok = false;
for(int i = 0;i<5;++i){
if(v[i].size() != 0){
tot *= v[i].size();
}else{
notok = true;
break;
}
}
if(tot < tar || notok){
printf("NO\n");
continue;
}else{
for(int i = 0;i<5;++i) sort(v[i].begin(),v[i].end());
memset(num,0,sizeof num);
int now = 1;
for(int i = 4;i>=0;--i){
if(v[i].size() != 0){
num[i] = now;
now *= v[i].size();
}
}
ans.clear();
temp = tar;
dfs(0);
for(int i = 0;i<ans.size();++i) printf("%c",ans[i]);
printf("\n");
}
}
return 0;
}