题目链接：http://www.lydsy.com/JudgeOnline/problem.php?id=4511
题意：求最长连续子序列满足元素和%7=0
维护前缀和，记录每个余数出现的最早位置即可...
随便卡卡常，只有 rk4...
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#include <cstdio> #include <iostream> #define N 50010 char xB[1<<15],*xS=xB,*xT=xB; #define getchar() (xS==xT&&(xT=(xS=xB)+fread(xB,1,1<<15,stdin),xS==xT)?0:*xS++) inline int read() { int x=0,f=1;char ch=getchar(); while(ch<'0'|ch>'9'){if(ch=='-')f=-1;ch=getchar();} while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} return x*f; } int a[N],sum[N]; int vis[10],n; int Mx(int a,int b) {return a>b?a:b;} int main() { int n=read(); for(int i=1;i<=n;i++) { int tmp=read(); sum[i]=(sum[i-1]+tmp)%7; } int cnt=0; for(int i=1;i<=n;i++) !vis[sum[i]]?vis[sum[i]]=i:cnt=Mx(cnt,i-vis[sum[i]]); printf("%d\n",cnt); } |
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