Lonlife-ACM 1014 - Absolute Defeat [差分]

DESCRIPTION

Eric has an array of integers $a_1,a_2,...,a_n$

. Every time, he can choose a contiguous subsequence of length $k$ and increase every integer in the contiguous subsequence by $1$.He wants the minimum value of the array is at least $m$

. Help him find the minimum number of operations needed.

INPUT

There are multiple test cases. The first line of input contains an integer$T$

, indicating the number of test cases. For each test case:The first line contains three integers$n$,$m$ and$k$$(1\le n\le {10}^5,1\le k\le n,1\le m\le {10}^4)$.The second line contains $n$ integers$a_1,a_2,...,a_n$$(1\le a_i\le {10}^4)$

.

OUTPUT

For each test case, output an integer denoting the minimum number of operations needed.

SAMPLE INPUT

32 2 21 15 1 41 2 3 4 54 10 31 2 3 4

SAMPLE OUTPUT

1015

SOLUTION

#include<cstdio>#include<iostream>#include<algorithm>#include<cstring>#include<cmath>using namespace std;int T;#define maxn 100010int a[maxn],d[maxn];int n,m,k;int main(){scanf("%d",&T);while(T--){scanf("%d%d%d",&n,&m,&k);int tot = 0,sum = 0;for(int i=1;i<=n;i++){scanf("%d",&a[i]);d[i]=a[i]-a[i-1];}for(int i=1;i<=n;i++){sum+=d[i];if(sum<m){tot += m-sum;if(i+k<=n)d[i+k] -= m-sum;sum += m-sum;}}printf("%d\n",tot);}return 0;}