输入一组数，m次询问

问每一个询问区间的逆序数有多少

区间DP简单题

#include "stdio.h"#include "string.h"int dp[1010][1010],a[1010];int main(){    int n,m,i,j,k;    while (scanf("%d%d",&n,&m)!=EOF)    {        for (i=1;i<=n;i++)            scanf("%d",&a[i]);        memset(dp,0,sizeof(dp));        for (i=1;i<=n;i++)            for (j=1;j+i-1<=n;j++)            {                k=i+j-1;                dp[j][k]=dp[j+1][k]+dp[j][k-1]-dp[j+1][k-1];                if (a[j]>a[k])                    dp[j][k]++;            }        while (m--)        {            scanf("%d%d",&i,&j);            printf("%d\n",dp[i][j]);        }    }    return 0;}