UVa 1450 Ariport
方法：二分
二分答案，检查的时候，记录下当前round之前能飞走的飞机数。如果一个方向为空，另一个方向有飞机，那就让另一个方向飞走一架飞机。如果两边边飞机数超过二分的限制的部分超过可以飞走的飞机数，那就返回false。注意，设置不需要更新当前飞机的数量。
code：
1 #include <cstdio> 2 #include <cstring> 3 #include <algorithm> 4 #include <iostream> 5 #include <string> 6 #include <vector> 7 #include <stack> 8 #include <bitset> 9 #include <cstdlib> 10 #include <cmath> 11 #include <set> 12 #include <list> 13 #include <deque> 14 #include <map> 15 #include <queue> 16 #include <fstream> 17 #include <cassert> 18 #include <unordered_map> 19 #include <unordered_set> 20 #include <cmath> 21 #include <sstream> 22 #include <time.h> 23 #include <complex> 24 #include <iomanip> 25 #define Max(a,b) ((a)>(b)?(a):(b)) 26 #define Min(a,b) ((a)<(b)?(a):(b)) 27 #define FOR(a,b,c) for (ll (a)=(b);(a)<(c);++(a)) 28 #define FORN(a,b,c) for (ll (a)=(b);(a)<=(c);++(a)) 29 #define DFOR(a,b,c) for (ll (a)=(b);(a)>=(c);--(a)) 30 #define FORSQ(a,b,c) for (ll (a)=(b);(a)*(a)<=(c);++(a)) 31 #define FORC(a,b,c) for (char (a)=(b);(a)<=(c);++(a)) 32 #define FOREACH(a,b) for (auto &(a) : (b)) 33 #define rep(i,n) FOR(i,0,n) 34 #define repn(i,n) FORN(i,1,n) 35 #define drep(i,n) DFOR(i,n-1,0) 36 #define drepn(i,n) DFOR(i,n,1) 37 #define MAX(a,b) a = Max(a,b) 38 #define MIN(a,b) a = Min(a,b) 39 #define SQR(x) ((LL)(x) * (x)) 40 #define Reset(a,b) memset(a,b,sizeof(a)) 41 #define fi first 42 #define se second 43 #define mp make_pair 44 #define pb push_back 45 #define all(v) v.begin(),v.end() 46 #define ALLA(arr,sz) arr,arr+sz 47 #define SIZE(v) (int)v.size() 48 #define SORT(v) sort(all(v)) 49 #define REVERSE(v) reverse(ALL(v)) 50 #define SORTA(arr,sz) sort(ALLA(arr,sz)) 51 #define REVERSEA(arr,sz) reverse(ALLA(arr,sz)) 52 #define PERMUTE next_permutation 53 #define TC(t) while(t--) 54 #define forever for(;;) 55 #define PINF 1000000000000 56 #define newline '\n' 57 58 #define test if(1)if(0)cerr 59 using namespace std; 60 using namespace std; 61 typedef vector<int> vi; 62 typedef vector<vi> vvi; 63 typedef pair<int,int> ii; 64 typedef pair<double,double> dd; 65 typedef pair<char,char> cc; 66 typedef vector<ii> vii; 67 typedef long long ll; 68 typedef unsigned long long ull; 69 typedef pair<ll, ll> l4; 70 const double pi = acos(-1.0); 71 72 const int maxn = 5e3+5; 73 int a[2][maxn]; 74 int n; 75 bool valid(int mid) 76 { 77 int r[2]={0,0}, moves = 0; 78 repn(i, n) 79 { 80 rep(j, 2) r[j] += a[j][i]; 81 int cut = 0; 82 rep(j, 2) if (r[j] > mid+1) 83 { 84 cut += r[j]-mid-1; 85 } 86 if (cut > moves) return false; 87 if (!r[0] && r[1]) r[1] -= 1; 88 else if (r[0] && !r[1]) r[0] -= 1; 89 else if (r[0] && r[1] && r[0] + r[1] > moves) 90 ++moves; 91 } 92 return true; 93 } 94 int main() 95 { 96 ios::sync_with_stdio(false); 97 cin.tie(0); 98 int T; cin >> T; 99 repn(kase, T) 100 { 101 cin >> n; 102 repn(i, n) rep(j, 2) cin >> a[j][i]; 103 int left = 0, right = 1e5+5, mid, ans=0; 104 while (left <= right) 105 { 106 mid = (left+right)>>1; 107 if (valid(mid)) 108 { 109 ans = mid; 110 right = mid-1; 111 } 112 else 113 left = mid+1; 114 } 115 cout << ans << newline; 116 } 117 } 118 /* 119 3 120 1 121 1 1 122 3 123 3 2 124 0 3 125 2 0 126 6 127 0 1 128 1 1 129 1 2 130 1 1 131 1 1 132 6 0 133 */
