本文共 4805 字，大约阅读时间需要 16 分钟。
题目链接：
给定 N，K ，N 每次可以 +1，-1，*2，问 N 变到 K 最少要几次变化？
1 #include 2 #include 3 #include 4 #include 5 #include 6 #include 7 #include 8 #include 9 #include 10 #include 11 #include 12 #include 13 #include 14 #include 15 #include 16 #include 17 #include 18 using namespace std; 19 20 #define INIT() ios::sync_with_stdio(false);cin.tie(0);cout.tie(0); 21 #define Rep(i,n) for (int i = 0; i < (n); ++i) 22 #define For(i,s,t) for (int i = (s); i <= (t); ++i) 23 #define rFor(i,t,s) for (int i = (t); i >= (s); --i) 24 #define ForLL(i, s, t) for (LL i = LL(s); i <= LL(t); ++i) 25 #define rForLL(i, t, s) for (LL i = LL(t); i >= LL(s); --i) 26 #define foreach(i,c) for (__typeof(c.begin()) i = c.begin(); i != c.end(); ++i) 27 #define rforeach(i,c) for (__typeof(c.rbegin()) i = c.rbegin(); i != c.rend(); ++i) 28 29 #define pr(x) cout << #x << " = " << x << " " 30 #define prln(x) cout << #x << " = " << x << endl 31 32 #define LOWBIT(x) ((x)&(-x)) 33 34 #define ALL(x) x.begin(),x.end() 35 #define INS(x) inserter(x,x.begin()) 36 #define UNIQUE(x) x.erase(unique(x.begin(), x.end()), x.end()) 37 #define REMOVE(x, c) x.erase(remove(x.begin(), x.end(), c), x.end()); // 删去 x 中所有 c 38 #define TOLOWER(x) transform(x.begin(), x.end(), x.begin(),::tolower); 39 #define TOUPPER(x) transform(x.begin(), x.end(), x.begin(),::toupper); 40 41 #define ms0(a) memset(a,0,sizeof(a)) 42 #define msI(a) memset(a,inf,sizeof(a)) 43 #define msM(a) memset(a,-1,sizeof(a)) 44 45 #define MP make_pair 46 #define PB push_back 47 #define ft first 48 #define sd second 49 50 template 51 istream &operator>>(istream &in, pair &p) { 52 in >> p.first >> p.second; 53 return in; 54 } 55 56 template 57 istream &operator>>(istream &in, vector &v) { 58 for (auto &x: v) 59 in >> x; 60 return in; 61 } 62 63 template 64 ostream &operator<<(ostream &out, const std::pair &p) { 65 out << "[" << p.first << ", " << p.second << "]" << "\n"; 66 return out; 67 } 68 69 inline int gc(){ 70 static const int BUF = 1e7; 71 static char buf[BUF], *bg = buf + BUF, *ed = bg; 72 73 if(bg == ed) fread(bg = buf, 1, BUF, stdin); 74 return *bg++; 75 } 76 77 inline int ri(){ 78 int x = 0, f = 1, c = gc(); 79 for(; c<48||c>57; f = c=='-'?-1:f, c=gc()); 80 for(; c>47&&c<58; x = x*10 + c - 48, c=gc()); 81 return x*f; 82 } 83 84 template 85 inline string toString(T x) { 86 ostringstream sout; 87 sout << x; 88 return sout.str(); 89 } 90 91 inline int toInt(string s) { 92 int v; 93 istringstream sin(s); 94 sin >> v; 95 return v; 96 } 97 98 //min <= aim <= max 99 template 100 inline bool BETWEEN(const T aim, const T min, const T max) {101 return min <= aim && aim <= max;102 }103 104 typedef long long LL;105 typedef unsigned long long uLL;106 typedef pair< double, double > PDD;107 typedef pair< int, int > PII;108 typedef pair< int, PII > PIPII;109 typedef pair< string, int > PSI;110 typedef pair< int, PSI > PIPSI;111 typedef set< int > SI;112 typedef set< PII > SPII;113 typedef vector< int > VI;114 typedef vector< double > VD;115 typedef vector< VI > VVI;116 typedef vector< SI > VSI;117 typedef vector< PII > VPII;118 typedef map< int, int > MII;119 typedef map< int, string > MIS;120 typedef map< int, PII > MIPII;121 typedef map< PII, int > MPIII;122 typedef map< string, int > MSI;123 typedef map< string, string > MSS;124 typedef map< PII, string > MPIIS;125 typedef map< PII, PII > MPIIPII;126 typedef multimap< int, int > MMII;127 typedef multimap< string, int > MMSI;128 //typedef unordered_map< int, int > uMII;129 typedef pair< LL, LL > PLL;130 typedef vector< LL > VL;131 typedef vector< VL > VVL;132 typedef priority_queue< int > PQIMax;133 typedef priority_queue< int, VI, greater< int > > PQIMin;134 const double EPS = 1e-8;135 const LL inf = 0x3fffffff;136 const LL infLL = 0x3fffffffffffffffLL;137 const LL mod = 1e9 + 7;138 const int maxN = 1e5 + 7;139 const LL ONE = 1;140 const LL evenBits = 0xaaaaaaaaaaaaaaaa;141 const LL oddBits = 0x5555555555555555;142 143 int N, K, ans;144 queue< int > Q;145 bool vis[maxN];146 147 void bfs() {148 int cnt = 1;149 Q.push(N);150 151 while(!Q.empty()) {152 int tmp = Q.front(); Q.pop(); 153 --cnt;154 if(tmp == K) break;155 156 if(BETWEEN(tmp, 0, maxN) && !vis[tmp]) {157 vis[tmp] = true;158 Q.push(tmp - 1);159 Q.push(tmp + 1);160 Q.push(tmp * 2);161 }162 163 if(cnt == 0) {164 cnt = Q.size();165 ++ans;166 }167 }168 }169 170 int main(){171 //freopen("MyOutput.txt","w",stdout);172 //freopen("input.txt","r",stdin);173 INIT();174 cin >> N >> K;175 bfs();176 cout << ans << endl;177 return 0;178 }
转载于:https://www.cnblogs.com/zaq19970105/p/11134239.html
