classSolution{publicbooleanvalidMountainArray(int[] A){if(A.length <3)returnfalse;int index &#61;-1;int max &#61;-1;//最大值下标for(int i &#61;0; i < A.length; i&#43;&#43;){if(A[i]>&#61; max){max &#61; A[i];index &#61; i;}}//峰头不能在首项或者尾项if(index &#61;&#61;0|| index &#61;&#61; A.length -1){returnfalse;}//判断上山for(int i &#61;1; i <&#61; index; i&#43;&#43;){if(A[i -1]>&#61; A[i]){returnfalse;}}//判断下山for(int i &#61; index &#43;1; i < A.length; i&#43;&#43;){if(A[i -1]<&#61; A[i]){returnfalse;}}returntrue;} }