HDU 5246 超级赛亚ACMer （lower_bound 与 upper_bound）

题目链接 : 超级赛亚ACMer

 

看别人AC代码学会了一个C++STL  lower_bound

ForwardIter lower_bound(ForwardIter first, ForwardIter last,const _Tp& val)算法返回一个非递减序列[first, last)中的第一个大于等于值val的位置。

ForwardIter upper_bound(ForwardIter first, ForwardIter last, const _Tp& val)算法返回一个非递减序列[first, last)中第一个大于val的位置。

lower_bound和upper_bound如下图所示：

 

 

例如 a = [1, 2, 2, 3, 4, 4, 4]          

int a[10] = {1,2,3,4,4,4,4, 6};
lower_bound(a, a+8, 3) - a = 2, 即下标为2的那个数,要记得减去数组的首地址. 如果lower_bound(a, a+8, 5) - a = 7;

同理upper_bound

本人ＡＣ代码

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#include <cstdio> #include <cstdlib> #include <cstring> #include <cctype> #include <cmath> #include <algorithm> #include <vector> #include <queue> #include <stack> #include <map>   using namespace std;   const int inf = 0x3f; const int INF = 0x3f3f3f3f; const int maxn = 1e5+5; __int64 a[maxn]; int main() {     //freopen("1.txt", "r", stdin);     int T, t, n;     __int64 fig, k;     scanf("%d", &T);     for(t = 1; t <= T; t++)     {         scanf("%d %I64d %I64d", &n, &fig, &k);         for(int i = 0; i < n; i++)         {             scanf("%I64d", &a[i]);         }         sort(a, a+n);         int i, j;         printf("Case #%d:\n", t);         if(a[0] > fig)         {             puts("madan!");continue;         }         for(i = 0; i < n; i++)         {             if(a[i] > fig) break;         }         fig = a[i-1];         for(i = i-1; i < n-1;i++)         {             if(fig+k >= a[i] && fig+k < a[i+1])             {                 fig = a[i]; k--;             }         }         fig+k >= a[n-1] ? puts("why am I so diao?") : puts("madan!");     }     return 0; }

使用lower_bound 的代码

+ View Code?

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#include <set> #include <map> #include <queue> #include <cmath> #include <cstdio> #include <string> #include <vector> #include <cstdlib> #include <cstring> #include <iostream> #include <algorithm> using namespace std; typedef long long LL; typedef pair<int, int> PII; const int MAXN = 100000 + 10; LL dp[MAXN], a[MAXN], add[MAXN]; int n, m, k;   int main() {     int T;     scanf("%d", &T);     for(int cas = 1; cas <= T; ++ cas)     {         scanf("%d%d%d", &n, &m, &k);         for (int i = 0; i < n; ++ i)         {             scanf("%I64d", a + i);         }         printf("Case #%d:\n", cas);         sort(a, a + n);         if (a[0] > m)         {         puts("madan!");         continue;         }         int pt = lower_bound(a, a + n, m) - a;         if (a[pt] != m) -- pt;         LL st = a[pt];         for (; pt < n; ++ pt)         {             if (k + st >= a[pt] && k + st < a[pt + 1])             {                 st = a[pt]; -- k;             }         }         if (st + k >= a[n - 1]) puts("why am I so diao?");         else puts("madan!");     }     return 0; }