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题意：给出n个整数，给定整数S,求长度最短的连续序列，使它们的和大于或等于S
第一种，是求前缀和，然后用lower_bound来找
第二种，尺取法，
1 #include<iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include <cmath> 5 #include<stack> 6 #include<vector> 7 #include<map> 8 #include<set> 9 #include<queue> 10 #include<algorithm> 11 using namespace std; 12 13 typedef long long LL; 14 const int INF = (1<<30)-1; 15 const int mod=1000000007; 16 const int maxn=100005; 17 18 int n,S; 19 int a[maxn],sum[maxn]; 20 21 int main(){ 22 while(scanf("%d %d",&n,&S) != EOF){ 23 memset(a,0,sizeof(a)); 24 memset(sum,0,sizeof(sum)); 25 for(int i = 0;i < n;i++) scanf("%d",&a[i]); 26 sum[0] = a[0]; 27 for(int i = 1;i < n;i++) sum[i] = sum[i-1] + a[i]; 28 29 // for(int i =0;i <= n;i++) 30 // printf("sum[%d] = %d\n",i,sum[i]); 31 if(sum[n-1] < S){ 32 printf("0\n"); 33 } 34 else{ 35 int res = INF; 36 for(int s = 0;sum[s] + S <= sum[n-1];s++){ 37 int t = lower_bound(sum,sum + n,sum[s] + S) - sum; 38 res = min(res,t-s); 39 // printf("res = %d\n",res); 40 } 41 printf("%d\n",res); 42 } 43 } 44 return 0; 45 }
1 #include<iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include <cmath> 5 #include<stack> 6 #include<vector> 7 #include<map> 8 #include<set> 9 #include<queue> 10 #include<algorithm> 11 using namespace std; 12 13 typedef long long LL; 14 const int INF = (1<<30)-1; 15 const int mod=1000000007; 16 const int maxn=100005; 17 18 int a[maxn]; 19 int n,S; 20 21 void solve(){ 22 int t = 0,s = 0; 23 int res = INF; 24 int sum = 0; 25 for(;;){ 26 while(t < n && sum < S){ 27 sum += a[t++]; 28 } 29 if(sum < S) break; 30 res = min(res,t - s); 31 sum -= a[s++]; 32 } 33 if(res > n) res = 0; 34 printf("%d\n",res); 35 } 36 37 int main(){ 38 while(scanf("%d %d",&n,&S) != EOF){ 39 memset(a,0,sizeof(a)); 40 for(int i = 0;i < n;i++) scanf("%d",&a[i]); 41 solve(); 42 } 43 return 0; 44 }
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原文地址：http://www.cnblogs.com/wuyuewoniu/p/4629936.html
